diff --git a/Build/Notepad3.ini b/Build/Notepad3.ini
index c40e9d859..f666dcc02 100644
Binary files a/Build/Notepad3.ini and b/Build/Notepad3.ini differ
diff --git a/scintilla/include/Platform.h b/scintilla/include/Platform.h
index 92180b354..de661dba5 100644
--- a/scintilla/include/Platform.h
+++ b/scintilla/include/Platform.h
@@ -99,7 +99,7 @@ class Point {
 	XYPOSITION x;
 	XYPOSITION y;
 
-	explicit Point(XYPOSITION x_=0, XYPOSITION y_=0) : x(x_), y(y_) {
+	constexpr explicit Point(XYPOSITION x_=0, XYPOSITION y_=0) : x(x_), y(y_) {
 	}
 
 	static Point FromInts(int x_, int y_) {
@@ -217,15 +217,15 @@ class ColourDesired {
 		return co;
 	}
 
-	unsigned int GetRed() const {
+	unsigned char GetRed() const {
 		return co & 0xff;
 	}
 
-	unsigned int GetGreen() const {
+	unsigned char GetGreen() const {
 		return (co >> 8) & 0xff;
 	}
 
-	unsigned int GetBlue() const {
+	unsigned char GetBlue() const {
 		return (co >> 16) & 0xff;
 	}
 };
diff --git a/scintilla/lexers/LexHTML.cxx b/scintilla/lexers/LexHTML.cxx
index e17ba116c..948617184 100644
--- a/scintilla/lexers/LexHTML.cxx
+++ b/scintilla/lexers/LexHTML.cxx
@@ -58,7 +58,7 @@ inline bool IsOperator(int ch) {
 static void GetTextSegment(Accessor &styler, Sci_PositionU start, Sci_PositionU end, char *s, size_t len) {
 	Sci_PositionU i = 0;
 	for (; (i < end - start + 1) && (i < len-1); i++) {
-		s[i] = static_cast<char>(MakeLowerCase(styler[start + i]));
+		s[i] = MakeLowerCase(styler[start + i]);
 	}
 	s[i] = '\0';
 }
@@ -267,7 +267,7 @@ static int classifyTagHTML(Sci_PositionU start, Sci_PositionU end,
 	for (Sci_PositionU cPos = start; cPos <= end && i < 30; cPos++) {
 		char ch = styler[cPos];
 		if ((ch != '<') && (ch != '/')) {
-			withSpace[i++] = caseSensitive ? ch : static_cast<char>(MakeLowerCase(ch));
+			withSpace[i++] = caseSensitive ? ch : MakeLowerCase(ch);
 		}
 	}
 
diff --git a/scintilla/lexlib/CharacterSet.cxx b/scintilla/lexlib/CharacterSet.cxx
index 791177fcc..2a1dabc1c 100644
--- a/scintilla/lexlib/CharacterSet.cxx
+++ b/scintilla/lexlib/CharacterSet.cxx
@@ -18,8 +18,8 @@ namespace Scintilla {
 int CompareCaseInsensitive(const char *a, const char *b) {
 	while (*a && *b) {
 		if (*a != *b) {
-			const char upperA = static_cast<char>(MakeUpperCase(*a));
-			const char upperB = static_cast<char>(MakeUpperCase(*b));
+			const char upperA = MakeUpperCase(*a);
+			const char upperB = MakeUpperCase(*b);
 			if (upperA != upperB)
 				return upperA - upperB;
 		}
@@ -33,8 +33,8 @@ int CompareCaseInsensitive(const char *a, const char *b) {
 int CompareNCaseInsensitive(const char *a, const char *b, size_t len) {
 	while (*a && *b && len) {
 		if (*a != *b) {
-			const char upperA = static_cast<char>(MakeUpperCase(*a));
-			const char upperB = static_cast<char>(MakeUpperCase(*b));
+			const char upperA = MakeUpperCase(*a);
+			const char upperB = MakeUpperCase(*b);
 			if (upperA != upperB)
 				return upperA - upperB;
 		}
diff --git a/scintilla/lexlib/CharacterSet.h b/scintilla/lexlib/CharacterSet.h
index be906ceaa..5965f38ca 100644
--- a/scintilla/lexlib/CharacterSet.h
+++ b/scintilla/lexlib/CharacterSet.h
@@ -167,16 +167,18 @@ inline bool isoperator(int ch) {
 	return false;
 }
 
-// Simple case functions for ASCII.
+// Simple case functions for ASCII supersets.
 
-inline int MakeUpperCase(int ch) {
+template <typename T>
+inline T MakeUpperCase(T ch) {
 	if (ch < 'a' || ch > 'z')
 		return ch;
 	else
-		return static_cast<char>(ch - 'a' + 'A');
+		return ch - 'a' + 'A';
 }
 
-inline int MakeLowerCase(int ch) {
+template <typename T>
+inline T MakeLowerCase(T ch) {
 	if (ch < 'A' || ch > 'Z')
 		return ch;
 	else
diff --git a/scintilla/src/AutoComplete.cxx b/scintilla/src/AutoComplete.cxx
index 966df7d47..fc4f947a5 100644
--- a/scintilla/src/AutoComplete.cxx
+++ b/scintilla/src/AutoComplete.cxx
@@ -49,7 +49,7 @@ AutoComplete::~AutoComplete() {
 	}
 }
 
-bool AutoComplete::Active() const {
+bool AutoComplete::Active() const noexcept {
 	return active;
 }
 
@@ -70,7 +70,7 @@ void AutoComplete::SetStopChars(const char *stopChars_) {
 	stopChars = stopChars_;
 }
 
-bool AutoComplete::IsStopChar(char ch) {
+bool AutoComplete::IsStopChar(char ch) const noexcept {
 	return ch && (stopChars.find(ch) != std::string::npos);
 }
 
@@ -78,7 +78,7 @@ void AutoComplete::SetFillUpChars(const char *fillUpChars_) {
 	fillUpChars = fillUpChars_;
 }
 
-bool AutoComplete::IsFillUpChar(char ch) {
+bool AutoComplete::IsFillUpChar(char ch) const noexcept {
 	return ch && (fillUpChars.find(ch) != std::string::npos);
 }
 
@@ -86,7 +86,7 @@ void AutoComplete::SetSeparator(char separator_) {
 	separator = separator_;
 }
 
-char AutoComplete::GetSeparator() const {
+char AutoComplete::GetSeparator() const noexcept {
 	return separator;
 }
 
@@ -94,7 +94,7 @@ void AutoComplete::SetTypesep(char separator_) {
 	typesep = separator_;
 }
 
-char AutoComplete::GetTypesep() const {
+char AutoComplete::GetTypesep() const noexcept {
 	return typesep;
 }
 
diff --git a/scintilla/src/AutoComplete.h b/scintilla/src/AutoComplete.h
index ed14f1776..6440c13d4 100644
--- a/scintilla/src/AutoComplete.h
+++ b/scintilla/src/AutoComplete.h
@@ -45,7 +45,7 @@ class AutoComplete {
 	~AutoComplete();
 
 	/// Is the auto completion list displayed?
-	bool Active() const;
+	bool Active() const noexcept;
 
 	/// Display the auto completion list positioned to be near a character position
 	void Start(Window &parent, int ctrlID, Sci::Position position, Point location,
@@ -53,19 +53,19 @@ class AutoComplete {
 
 	/// The stop chars are characters which, when typed, cause the auto completion list to disappear
 	void SetStopChars(const char *stopChars_);
-	bool IsStopChar(char ch);
+	bool IsStopChar(char ch) const noexcept;
 
 	/// The fillup chars are characters which, when typed, fill up the selected word
 	void SetFillUpChars(const char *fillUpChars_);
-	bool IsFillUpChar(char ch);
+	bool IsFillUpChar(char ch) const noexcept;
 
 	/// The separator character is used when interpreting the list in SetList
 	void SetSeparator(char separator_);
-	char GetSeparator() const;
+	char GetSeparator() const noexcept;
 
 	/// The typesep character is used for separating the word from the type
 	void SetTypesep(char separator_);
-	char GetTypesep() const;
+	char GetTypesep() const noexcept;
 
 	/// The list string contains a sequence of words separated by the separator character
 	void SetList(const char *list);
diff --git a/scintilla/src/CallTip.cxx b/scintilla/src/CallTip.cxx
index 3d62dba88..f8bb77c48 100644
--- a/scintilla/src/CallTip.cxx
+++ b/scintilla/src/CallTip.cxx
@@ -8,6 +8,7 @@
 #include <cstdlib>
 #include <cstring>
 #include <cstdio>
+#include <cmath>
 
 #include <stdexcept>
 #include <string>
@@ -150,7 +151,7 @@ void CallTip::DrawChunk(Surface *surface, int &x, const char *s,
 			} else if (IsTabCharacter(s[startSeg])) {
 				xEnd = NextTabPos(x);
 			} else {
-				xEnd = x + RoundXYPosition(surface->WidthText(font, s + startSeg, endSeg - startSeg));
+				xEnd = x + static_cast<int>(lround(surface->WidthText(font, s + startSeg, endSeg - startSeg)));
 				if (draw) {
 					rcClient.left = static_cast<XYPOSITION>(x);
 					rcClient.right = static_cast<XYPOSITION>(xEnd);
@@ -172,7 +173,7 @@ int CallTip::PaintContents(Surface *surfaceWindow, bool draw) {
 	PRectangle rcClient(1.0f, 1.0f, rcClientSize.right - 1, rcClientSize.bottom - 1);
 
 	// To make a nice small call tip window, it is only sized to fit most normal characters without accents
-	const int ascent = RoundXYPosition(surfaceWindow->Ascent(font) - surfaceWindow->InternalLeading(font));
+	const int ascent = static_cast<int>(lround(surfaceWindow->Ascent(font) - surfaceWindow->InternalLeading(font)));
 
 	// For each line...
 	// Draw the definition in three parts: before highlight, highlighted, after highlight
@@ -184,7 +185,7 @@ int CallTip::PaintContents(Surface *surfaceWindow, bool draw) {
 
 	while (moreChunks) {
 		const char *chunkEnd = strchr(chunkVal, '\n');
-		if (chunkEnd == NULL) {
+		if (!chunkEnd) {
 			chunkEnd = chunkVal + strlen(chunkVal);
 			moreChunks = false;
 		}
@@ -253,7 +254,7 @@ void CallTip::MouseClick(Point pt) {
 PRectangle CallTip::CallTipStart(Sci::Position pos, Point pt, int textHeight, const char *defn,
                                  const char *faceName, int size,
                                  int codePage_, int characterSet,
-								 int technology, Window &wParent) {
+								 int technology, const Window &wParent) {
 	clickPlace = 0;
 	val = defn;
 	codePage = codePage_;
@@ -270,18 +271,12 @@ PRectangle CallTip::CallTipStart(Sci::Position pos, Point pt, int textHeight, co
 	font.Create(fp);
 	// Look for multiple lines in the text
 	// Only support \n here - simply means container must avoid \r!
-	int numLines = 1;
-	const char *newline;
-	const char *look = val.c_str();
+	const int numLines = 1 + static_cast<int>(std::count(val.begin(), val.end(), '\n'));
 	rectUp = PRectangle(0,0,0,0);
 	rectDown = PRectangle(0,0,0,0);
 	offsetMain = insetX;            // changed to right edge of any arrows
 	const int width = PaintContents(surfaceMeasure.get(), false) + insetX;
-	while ((newline = strchr(look, '\n')) != NULL) {
-		look = newline + 1;
-		numLines++;
-	}
-	lineHeight = RoundXYPosition(surfaceMeasure->Height(font));
+	lineHeight = static_cast<int>(lround(surfaceMeasure->Height(font)));
 
 	// The returned
 	// rectangle is aligned to the right edge of the last arrow encountered in
diff --git a/scintilla/src/CallTip.h b/scintilla/src/CallTip.h
index cb5d2c12c..9c00a777d 100644
--- a/scintilla/src/CallTip.h
+++ b/scintilla/src/CallTip.h
@@ -63,7 +63,7 @@ class CallTip {
 	/// Setup the calltip and return a rectangle of the area required.
 	PRectangle CallTipStart(Sci::Position pos, Point pt, int textHeight, const char *defn,
 		const char *faceName, int size, int codePage_,
-		int characterSet, int technology, Window &wParent);
+		int characterSet, int technology, const Window &wParent);
 
 	void CallTipCancel();
 
diff --git a/scintilla/src/ContractionState.cxx b/scintilla/src/ContractionState.cxx
index b513c20a6..57d9b7a1c 100644
--- a/scintilla/src/ContractionState.cxx
+++ b/scintilla/src/ContractionState.cxx
@@ -286,7 +286,8 @@ bool ContractionState<LINE>::SetFoldDisplayText(Sci::Line lineDoc, const char *t
 	EnsureData();
 	const char *foldText = foldDisplayTexts->ValueAt(lineDoc).get();
 	if (!foldText || !text || 0 != strcmp(text, foldText)) {
-		foldDisplayTexts->SetValueAt(lineDoc, UniqueStringCopy(text));
+		UniqueString uns = UniqueStringCopy(text);
+		foldDisplayTexts->SetValueAt(lineDoc, std::move(uns));
 		Check();
 		return true;
 	} else {
diff --git a/scintilla/src/EditView.cxx b/scintilla/src/EditView.cxx
index 772cc3cd1..adb0305ba 100644
--- a/scintilla/src/EditView.cxx
+++ b/scintilla/src/EditView.cxx
@@ -19,6 +19,7 @@
 #include <map>
 #include <forward_list>
 #include <algorithm>
+#include <iterator>
 #include <memory>
 
 #include "Platform.h"
@@ -86,9 +87,9 @@ static int WidthStyledText(Surface *surface, const ViewStyle &vs, int styleOffse
 	int width = 0;
 	size_t start = 0;
 	while (start < len) {
-		const size_t style = styles[start];
+		const unsigned char style = styles[start];
 		size_t endSegment = start;
-		while ((endSegment + 1 < len) && (static_cast<size_t>(styles[endSegment + 1]) == style))
+		while ((endSegment + 1 < len) && (styles[endSegment + 1] == style))
 			endSegment++;
 		FontAlias fontText = vs.styles[style + styleOffset].font;
 		width += static_cast<int>(surface->WidthText(fontText, text + start,
@@ -280,13 +281,13 @@ void EditView::AllocateGraphics(const ViewStyle &vsDraw) {
 }
 
 static const char *ControlCharacterString(unsigned char ch) {
-	const char *reps[] = {
+	const char * const reps[] = {
 		"NUL", "SOH", "STX", "ETX", "EOT", "ENQ", "ACK", "BEL",
 		"BS", "HT", "LF", "VT", "FF", "CR", "SO", "SI",
 		"DLE", "DC1", "DC2", "DC3", "DC4", "NAK", "SYN", "ETB",
 		"CAN", "EM", "SUB", "ESC", "FS", "GS", "RS", "US"
 	};
-	if (ch < ELEMENTS(reps)) {
+	if (ch < std::size(reps)) {
 		return reps[ch];
 	} else {
 		return "BAD";
@@ -433,15 +434,15 @@ void EditView::LayoutLine(const EditModel &model, Sci::Line line, Surface *surfa
 			for (int charInLine = 0; charInLine<lineLength; charInLine++) {
 				const char chDoc = ll->chars[charInLine];
 				if (vstyle.styles[ll->styles[charInLine]].caseForce == Style::caseUpper)
-					ll->chars[charInLine] = static_cast<char>(MakeUpperCase(chDoc));
+					ll->chars[charInLine] = MakeUpperCase(chDoc);
 				else if (vstyle.styles[ll->styles[charInLine]].caseForce == Style::caseLower)
-					ll->chars[charInLine] = static_cast<char>(MakeLowerCase(chDoc));
+					ll->chars[charInLine] = MakeLowerCase(chDoc);
 				else if (vstyle.styles[ll->styles[charInLine]].caseForce == Style::caseCamel) {
 					if ((model.pdoc->IsASCIIWordByte(ll->chars[charInLine])) &&
 					  ((charInLine == 0) || (!model.pdoc->IsASCIIWordByte(ll->chars[charInLine - 1])))) {
-						ll->chars[charInLine] = static_cast<char>(MakeUpperCase(chDoc));
+						ll->chars[charInLine] = MakeUpperCase(chDoc);
 					} else {
-						ll->chars[charInLine] = static_cast<char>(MakeLowerCase(chDoc));
+						ll->chars[charInLine] = MakeLowerCase(chDoc);
 					}
 				}
 			}
@@ -722,7 +723,7 @@ SelectionPosition EditView::SPositionFromLineX(Surface *surface, const EditModel
 			return SelectionPosition(model.pdoc->MovePositionOutsideChar(positionInLine + posLineStart, 1));
 		}
 #ifdef NP3_MATCH_BRACE_RECT_SEL_PATCH
-        const XYPOSITION spaceWidth = EndSpaceWidth(model,vs,ll,lineDoc);
+    const XYPOSITION spaceWidth = EndSpaceWidth(model,vs,ll,lineDoc);
 #else
 		const XYPOSITION spaceWidth = vs.styles[ll->EndLineStyle()].spaceWidth;
 #endif
@@ -810,10 +811,10 @@ static ColourDesired TextBackground(const EditModel &model, const ViewStyle &vsD
 	}
 }
 
-void EditView::DrawIndentGuide(Surface *surface, Sci::Line lineVisible, int lineHeight, Sci::Position start, PRectangle rcSegment, bool highlight) {
+void EditView::DrawIndentGuide(Surface *surface, Sci::Line lineVisible, int lineHeight, XYPOSITION start, PRectangle rcSegment, bool highlight) {
 	const Point from = Point::FromInts(0, ((lineVisible & 1) && (lineHeight & 1)) ? 1 : 0);
-	const PRectangle rcCopyArea = PRectangle::FromInts(static_cast<int>(start + 1), static_cast<int>(rcSegment.top),
-		static_cast<int>(start + 2), static_cast<int>(rcSegment.bottom));
+	const PRectangle rcCopyArea(start + 1, rcSegment.top,
+		start + 2, rcSegment.bottom);
 	surface->Copy(rcCopyArea, from,
 		highlight ? *pixmapIndentGuideHighlight : *pixmapIndentGuide);
 }
@@ -938,7 +939,7 @@ void EditView::DrawEOL(Surface *surface, const EditModel &model, const ViewStyle
 			rcSegment.left = xStart + ll->positions[eolPos] - static_cast<XYPOSITION>(subLineStart)+virtualSpace;
 			rcSegment.right = xStart + ll->positions[eolPos + 1] - static_cast<XYPOSITION>(subLineStart)+virtualSpace;
 			blobsWidth += rcSegment.Width();
-			char hexits[4];
+			char hexits[4] = "";
 			const char *ctrlChar;
 			const unsigned char chEOL = ll->chars[eolPos];
 			const int styleMain = ll->styles[eolPos];
@@ -1188,8 +1189,8 @@ void EditView::DrawFoldDisplayText(Surface *surface, const EditModel &model, con
 		if (model.foldDisplayTextStyle == SC_FOLDDISPLAYTEXT_BOXED) {
 			surface->PenColour(textFore);
 			PRectangle rcBox = rcSegment;
-			rcBox.left = static_cast<XYPOSITION>(RoundXYPosition(rcSegment.left));
-			rcBox.right = static_cast<XYPOSITION>(RoundXYPosition(rcSegment.right));
+			rcBox.left = round(rcSegment.left);
+			rcBox.right = round(rcSegment.right);
 			surface->MoveTo(static_cast<int>(rcBox.left), static_cast<int>(rcBox.top));
 			surface->LineTo(static_cast<int>(rcBox.left), static_cast<int>(rcBox.bottom));
 			surface->MoveTo(static_cast<int>(rcBox.right), static_cast<int>(rcBox.top));
@@ -1391,7 +1392,7 @@ void EditView::DrawCarets(Surface *surface, const EditModel &model, const ViewSt
 				xposCaret += xStart;
 				if (model.posDrag.IsValid()) {
 					/* Dragging text, use a line caret */
-					rcCaret.left = static_cast<XYPOSITION>(RoundXYPosition(xposCaret - caretWidthOffset));
+					rcCaret.left = round(xposCaret - caretWidthOffset);
 					rcCaret.right = rcCaret.left + vsDraw.caretWidth;
 				} else if (model.inOverstrike && drawOverstrikeCaret) {
 					/* Overstrike (insert mode), use a modified bar caret */
@@ -1409,7 +1410,7 @@ void EditView::DrawCarets(Surface *surface, const EditModel &model, const ViewSt
 					}
 				} else {
 					/* Line caret */
-					rcCaret.left = static_cast<XYPOSITION>(RoundXYPosition(xposCaret - caretWidthOffset));
+					rcCaret.left = round(xposCaret - caretWidthOffset);
 					rcCaret.right = rcCaret.left + vsDraw.caretWidth;
 				}
 				const ColourDesired caretColour = mainCaret ? vsDraw.caretcolour : vsDraw.additionalCaretColour;
@@ -1725,7 +1726,7 @@ void EditView::DrawForeground(Surface *surface, const EditModel &model, const Vi
 							indentCount <= (ll->positions[i + 1] - epsilon) / indentWidth;
 							indentCount++) {
 							if (indentCount > 0) {
-								const int xIndent = static_cast<int>(indentCount * indentWidth);
+								const XYPOSITION xIndent = floor(indentCount * indentWidth);
 								DrawIndentGuide(surface, lineVisible, vsDraw.lineHeight, xIndent + xStart, rcSegment,
 									(ll->xHighlightGuide == xIndent));
 							}
@@ -1804,7 +1805,7 @@ void EditView::DrawForeground(Surface *surface, const EditModel &model, const Vi
 									indentCount <= (ll->positions[cpos + ts.start + 1] - epsilon) / indentWidth;
 									indentCount++) {
 									if (indentCount > 0) {
-										const int xIndent = static_cast<int>(indentCount * indentWidth);
+										const XYPOSITION xIndent = floor(indentCount * indentWidth);
 										DrawIndentGuide(surface, lineVisible, vsDraw.lineHeight, xIndent + xStart, rcSegment,
 											(ll->xHighlightGuide == xIndent));
 									}
@@ -1881,7 +1882,7 @@ void EditView::DrawIndentGuidesOverEmpty(Surface *surface, const EditModel &mode
 		}
 
 		for (int indentPos = model.pdoc->IndentSize(); indentPos < indentSpace; indentPos += model.pdoc->IndentSize()) {
-			const int xIndent = static_cast<int>(indentPos * vsDraw.spaceWidth);
+			const XYPOSITION xIndent = floor(indentPos * vsDraw.spaceWidth);
 			if (xIndent < xStartText) {
 				DrawIndentGuide(surface, lineVisible, vsDraw.lineHeight, xIndent + xStart, rcLine,
 					(ll->xHighlightGuide == xIndent));
@@ -2215,7 +2216,7 @@ static ColourDesired InvertedLight(ColourDesired orig) {
 	return ColourDesired(std::min(r, 0xffu), std::min(g, 0xffu), std::min(b, 0xffu));
 }
 
-Sci::Position EditView::FormatRange(bool draw, Sci_RangeToFormat *pfr, Surface *surface, Surface *surfaceMeasure,
+Sci::Position EditView::FormatRange(bool draw, const Sci_RangeToFormat *pfr, Surface *surface, Surface *surfaceMeasure,
 	const EditModel &model, const ViewStyle &vs) {
 	// Can't use measurements cached for screen
 	posCache.Clear();
diff --git a/scintilla/src/EditView.h b/scintilla/src/EditView.h
index 387795bfc..7d8f6fe5e 100644
--- a/scintilla/src/EditView.h
+++ b/scintilla/src/EditView.h
@@ -126,7 +126,7 @@ class EditView {
 	Sci::Line DisplayFromPosition(Surface *surface, const EditModel &model, Sci::Position pos, const ViewStyle &vs);
 	Sci::Position StartEndDisplayLine(Surface *surface, const EditModel &model, Sci::Position pos, bool start, const ViewStyle &vs);
 
-	void DrawIndentGuide(Surface *surface, Sci::Line lineVisible, int lineHeight, Sci::Position start, PRectangle rcSegment, bool highlight);
+	void DrawIndentGuide(Surface *surface, Sci::Line lineVisible, int lineHeight, XYPOSITION start, PRectangle rcSegment, bool highlight);
 	void DrawEOL(Surface *surface, const EditModel &model, const ViewStyle &vsDraw, const LineLayout *ll, PRectangle rcLine,
 		Sci::Line line, Sci::Position lineEnd, int xStart, int subLine, XYACCUMULATOR subLineStart,
 		ColourOptional background);
@@ -150,7 +150,7 @@ class EditView {
 		const ViewStyle &vsDraw);
 	void FillLineRemainder(Surface *surface, const EditModel &model, const ViewStyle &vsDraw, const LineLayout *ll,
 		Sci::Line line, PRectangle rcArea, int subLine) const;
-	Sci::Position FormatRange(bool draw, Sci_RangeToFormat *pfr, Surface *surface, Surface *surfaceMeasure,
+	Sci::Position FormatRange(bool draw, const Sci_RangeToFormat *pfr, Surface *surface, Surface *surfaceMeasure,
 		const EditModel &model, const ViewStyle &vs);
 };
 
diff --git a/scintilla/src/Editor.cxx b/scintilla/src/Editor.cxx
index 554fd01dc..2e25080ea 100644
--- a/scintilla/src/Editor.cxx
+++ b/scintilla/src/Editor.cxx
@@ -19,6 +19,7 @@
 #include <map>
 #include <forward_list>
 #include <algorithm>
+#include <iterator>
 #include <memory>
 
 #include "Platform.h"
@@ -28,6 +29,7 @@
 #include "Scintilla.h"
 
 #include "StringCopy.h"
+#include "CharacterSet.h"
 #include "Position.h"
 #include "UniqueString.h"
 #include "SplitVector.h"
@@ -204,13 +206,13 @@ void Editor::SetRepresentations() {
 	reprs.Clear();
 
 	// C0 control set
-	const char *reps[] = {
+	const char * const reps[] = {
 		"NUL", "SOH", "STX", "ETX", "EOT", "ENQ", "ACK", "BEL",
 		"BS", "HT", "LF", "VT", "FF", "CR", "SO", "SI",
 		"DLE", "DC1", "DC2", "DC3", "DC4", "NAK", "SYN", "ETB",
 		"CAN", "EM", "SUB", "ESC", "FS", "GS", "RS", "US"
 	};
-	for (size_t j=0; j < ELEMENTS(reps); j++) {
+	for (size_t j=0; j < std::size(reps); j++) {
 		const char c[2] = { static_cast<char>(j), 0 };
 		reprs.SetRepresentation(c, reps[j]);
 	}
@@ -218,13 +220,13 @@ void Editor::SetRepresentations() {
 	// C1 control set
 	// As well as Unicode mode, ISO-8859-1 should use these
 	if (IsUnicodeMode()) {
-		const char *repsC1[] = {
+		const char * const repsC1[] = {
 			"PAD", "HOP", "BPH", "NBH", "IND", "NEL", "SSA", "ESA",
 			"HTS", "HTJ", "VTS", "PLD", "PLU", "RI", "SS2", "SS3",
 			"DCS", "PU1", "PU2", "STS", "CCH", "MW", "SPA", "EPA",
 			"SOS", "SGCI", "SCI", "CSI", "ST", "OSC", "PM", "APC"
 		};
-		for (size_t j=0; j < ELEMENTS(repsC1); j++) {
+		for (size_t j=0; j < std::size(repsC1); j++) {
 			const char c1[3] = { '\xc2',  static_cast<char>(0x80+j), 0 };
 			reprs.SetRepresentation(c1, repsC1[j]);
 		}
@@ -1632,7 +1634,7 @@ void Editor::LinesSplit(int pixelWidth) {
 	}
 }
 
-void Editor::PaintSelMargin(Surface *surfaceWindow, PRectangle &rc) {
+void Editor::PaintSelMargin(Surface *surfaceWindow, const PRectangle &rc) {
 	if (vs.fixedColumnWidth == 0)
 		return;
 
@@ -1777,7 +1779,7 @@ void Editor::Paint(Surface *surfaceWindow, PRectangle rcArea) {
 // This is mostly copied from the Paint method but with some things omitted
 // such as the margin markers, line numbers, selection and caret
 // Should be merged back into a combined Draw method.
-Sci::Position Editor::FormatRange(bool draw, Sci_RangeToFormat *pfr) {
+Sci::Position Editor::FormatRange(bool draw, const Sci_RangeToFormat *pfr) {
 	if (!pfr)
 		return 0;
 
@@ -2612,7 +2614,7 @@ void Editor::NotifyModified(Document *, DocModification mh, void *) {
 		if (mh.modificationType & SC_MOD_CHANGEANNOTATION) {
 			const Sci::Line lineDoc = pdoc->SciLineFromPosition(mh.position);
 			if (vs.annotationVisible) {
-				if (pcs->SetHeight(lineDoc, static_cast<int>(pcs->GetHeight(lineDoc) + mh.annotationLinesAdded))) {
+				if (pcs->SetHeight(lineDoc, pcs->GetHeight(lineDoc) + static_cast<int>(mh.annotationLinesAdded))) {
 					SetScrollBars();
 				}
 				Redraw();
@@ -4092,12 +4094,10 @@ std::string Editor::CaseMapString(const std::string &s, int caseMapping) {
 	for (char &ch : ret) {
 		switch (caseMapping) {
 			case cmUpper:
-				if (ch >= 'a' && ch <= 'z')
-					ch = static_cast<char>(ch - 'a' + 'A');
+				ch = MakeUpperCase(ch);
 				break;
 			case cmLower:
-				if (ch >= 'A' && ch <= 'Z')
-					ch = static_cast<char>(ch - 'A' + 'a');
+				ch = MakeLowerCase(ch);
 				break;
 		}
 	}
diff --git a/scintilla/src/Editor.h b/scintilla/src/Editor.h
index 523304ae5..39dd15c71 100644
--- a/scintilla/src/Editor.h
+++ b/scintilla/src/Editor.h
@@ -375,10 +375,10 @@ class Editor : public EditModel, public DocWatcher {
 	void LinesJoin();
 	void LinesSplit(int pixelWidth);
 
-	void PaintSelMargin(Surface *surfaceWindow, PRectangle &rc);
+	void PaintSelMargin(Surface *surfaceWindow, const PRectangle &rc);
 	void RefreshPixMaps(Surface *surfaceWindow);
 	void Paint(Surface *surfaceWindow, PRectangle rcArea);
-	Sci::Position FormatRange(bool draw, Sci_RangeToFormat *pfr);
+	Sci::Position FormatRange(bool draw, const Sci_RangeToFormat *pfr);
 	int TextWidth(int style, const char *text);
 
 	virtual void SetVerticalScrollPos() = 0;
diff --git a/scintilla/src/Indicator.cxx b/scintilla/src/Indicator.cxx
index 5e229039e..077d12740 100644
--- a/scintilla/src/Indicator.cxx
+++ b/scintilla/src/Indicator.cxx
@@ -5,6 +5,8 @@
 // Copyright 1998-2001 by Neil Hodgson <neilh@scintilla.org>
 // The License.txt file describes the conditions under which this software may be distributed.
 
+#include <cmath>
+
 #include <stdexcept>
 #include <vector>
 #include <map>
@@ -21,8 +23,8 @@ using namespace Scintilla;
 
 static PRectangle PixelGridAlign(const PRectangle &rc) {
 	// Move left and right side to nearest pixel to avoid blurry visuals
-	return PRectangle::FromInts(static_cast<int>(rc.left + 0.5), static_cast<int>(rc.top),
-		static_cast<int>(rc.right + 0.5), static_cast<int>(rc.bottom));
+	return PRectangle::FromInts(static_cast<int>(lround(rc.left)), static_cast<int>(rc.top),
+		static_cast<int>(lround(rc.right)), static_cast<int>(rc.bottom));
 }
 
 void Indicator::Draw(Surface *surface, const PRectangle &rc, const PRectangle &rcLine, const PRectangle &rcCharacter, DrawState drawState, int value) const {
@@ -36,8 +38,8 @@ void Indicator::Draw(Surface *surface, const PRectangle &rc, const PRectangle &r
 	surface->PenColour(sacDraw.fore);
 	const int ymid = static_cast<int>(rc.bottom + rc.top) / 2;
 	if (sacDraw.style == INDIC_SQUIGGLE) {
-		int x = static_cast<int>(rc.left+0.5);
-		const int xLast = static_cast<int>(rc.right+0.5);
+		int x = static_cast<int>(lround(rc.left));
+		const int xLast = static_cast<int>(lround(rc.right));
 		int y = 0;
 		surface->MoveTo(x, static_cast<int>(rc.top) + y);
 		while (x < xLast) {
@@ -175,7 +177,7 @@ void Indicator::Draw(Surface *surface, const PRectangle &rc, const PRectangle &r
 		if (rcCharacter.Width() >= 0.1) {
 			const int pixelHeight = static_cast<int>(rc.Height() - 1.0f);	// 1 pixel onto next line if multiphase
 			const XYPOSITION x = (sacDraw.style == INDIC_POINT) ? (rcCharacter.left) : ((rcCharacter.right + rcCharacter.left) / 2);
-			const int ix = static_cast<int>(x + 0.5f);
+			const int ix = static_cast<int>(lround(x));
 			const int iy = static_cast<int>(rc.top + 1.0f);
 			Point pts[] = {
 				Point::FromInts(ix - pixelHeight, iy + pixelHeight),	// Left
diff --git a/scintilla/src/RunStyles.cxx b/scintilla/src/RunStyles.cxx
index f92da5047..23392436b 100644
--- a/scintilla/src/RunStyles.cxx
+++ b/scintilla/src/RunStyles.cxx
@@ -6,9 +6,11 @@
 
 #include <cstddef>
 #include <cstdlib>
+#include <cstdint>
 #include <cstring>
 #include <cstdio>
 #include <cstdarg>
+#include <climits>
 
 #include <stdexcept>
 #include <vector>
@@ -306,5 +308,7 @@ void RunStyles<DISTANCE, STYLE>::Check() const {
 
 template class Scintilla::RunStyles<int, int>;
 template class Scintilla::RunStyles<int, char>;
+#if PTRDIFF_MAX != INT_MAX
 template class Scintilla::RunStyles<ptrdiff_t, int>;
 template class Scintilla::RunStyles<ptrdiff_t, char>;
+#endif
diff --git a/scintilla/src/Selection.h b/scintilla/src/Selection.h
index 88d225826..6530abf86 100644
--- a/scintilla/src/Selection.h
+++ b/scintilla/src/Selection.h
@@ -173,7 +173,7 @@ class Selection {
 	void AddSelectionWithoutTrim(SelectionRange range);
 	void DropSelection(size_t r);
 	void DropAdditionalRanges();
-	void TentativeSelection(const SelectionRange &range);
+  void TentativeSelection(const SelectionRange &range);
 	void CommitTentative();
 	int CharacterInSelection(Sci::Position posCharacter) const;
 	int InSelectionForEOL(Sci::Position pos) const;
diff --git a/scintilla/src/SparseVector.h b/scintilla/src/SparseVector.h
index 11a126a1a..0667e54c4 100644
--- a/scintilla/src/SparseVector.h
+++ b/scintilla/src/SparseVector.h
@@ -77,11 +77,11 @@ class SparseVector {
 			if (position == startPartition) {
 				// Already a value at this position, so replace
 				ClearValue(partition);
-				values->SetValueAt(partition, std::move(value));
+				values->SetValueAt(partition, std::forward<ParamType>(value));
 			} else {
 				// Insert a new element
 				starts->InsertPartition(partition + 1, position);
-				values->Insert(partition + 1, std::move(value));
+				values->Insert(partition + 1, std::forward<ParamType>(value));
 			}
 		}
 	}
diff --git a/scintilla/src/SplitVector.h b/scintilla/src/SplitVector.h
index 16dec6e98..3fb595eef 100644
--- a/scintilla/src/SplitVector.h
+++ b/scintilla/src/SplitVector.h
@@ -130,14 +130,14 @@ class SplitVector {
 			if (position < 0) {
 				;
 			} else {
-				body[position] = std::move(v);
+				body[position] = std::forward<ParamType>(v);
 			}
 		} else {
 			PLATFORM_ASSERT(position < lengthBody);
 			if (position >= lengthBody) {
 				;
 			} else {
-				body[gapLength + position] = std::move(v);
+				body[gapLength + position] = std::forward<ParamType>(v);
 			}
 		}
 	}
diff --git a/scintilla/src/XPM.cxx b/scintilla/src/XPM.cxx
index f83c3d6a8..04dc530bf 100644
--- a/scintilla/src/XPM.cxx
+++ b/scintilla/src/XPM.cxx
@@ -105,15 +105,15 @@ void XPM::Init(const char *const *linesForm) {
 
 	for (int c=0; c<nColours; c++) {
 		const char *colourDef = linesForm[c+1];
-		int code = static_cast<unsigned char>(colourDef[0]);
+		const char code = colourDef[0];
 		colourDef += 4;
 		ColourDesired colour(0xff, 0xff, 0xff);
 		if (*colourDef == '#') {
 			colour.Set(colourDef);
 		} else {
-			codeTransparent = static_cast<char>(code);
+			codeTransparent = code;
 		}
-		colourCodeTable[code] = colour;
+		colourCodeTable[static_cast<unsigned char>(code)] = colour;
 	}
 
 	for (int y=0; y<height; y++) {
@@ -152,7 +152,7 @@ void XPM::PixelAt(int x, int y, ColourDesired &colour, bool &transparent) const
 		transparent = true;
 		return;
 	}
-	int code = pixels[y * width + x];
+	const int code = pixels[y * width + x];
 	transparent = code == codeTransparent;
 	if (transparent) {
 		colour = ColourDesired(0);
@@ -234,9 +234,9 @@ const unsigned char *RGBAImage::Pixels() const {
 void RGBAImage::SetPixel(int x, int y, ColourDesired colour, int alpha) {
 	unsigned char *pixel = &pixelBytes[0] + (y*width+x) * 4;
 	// RGBA
-	pixel[0] = static_cast<unsigned char>(colour.GetRed());
-	pixel[1] = static_cast<unsigned char>(colour.GetGreen());
-	pixel[2] = static_cast<unsigned char>(colour.GetBlue());
+	pixel[0] = colour.GetRed();
+	pixel[1] = colour.GetGreen();
+	pixel[2] = colour.GetBlue();
 	pixel[3] = static_cast<unsigned char>(alpha);
 }
 
diff --git a/scintilla/src/XPM.h b/scintilla/src/XPM.h
index a2bd6cb91..2af0ae84e 100644
--- a/scintilla/src/XPM.h
+++ b/scintilla/src/XPM.h
@@ -59,7 +59,7 @@ class RGBAImage {
 	float GetScaledWidth() const { return width / scale; }
 	int CountBytes() const;
 	const unsigned char *Pixels() const;
-	void SetPixel(int x, int y, ColourDesired colour, int alpha=0xff);
+	void SetPixel(int x, int y, ColourDesired colour, int alpha);
 };
 
 /**
diff --git a/scintilla/win32/PlatWin.cxx b/scintilla/win32/PlatWin.cxx
index 8abf51913..a74a21238 100644
--- a/scintilla/win32/PlatWin.cxx
+++ b/scintilla/win32/PlatWin.cxx
@@ -188,6 +188,11 @@ struct FormatAndMetrics {
 		yInternalLeading(yInternalLeading_) {
 	}
 #endif
+	FormatAndMetrics(const FormatAndMetrics &) = delete;
+	FormatAndMetrics(FormatAndMetrics &&) = delete;
+	FormatAndMetrics &operator=(const FormatAndMetrics &) = delete;
+	FormatAndMetrics &operator=(FormatAndMetrics &&) = delete;
+
 	~FormatAndMetrics() {
 		if (hfont)
 			::DeleteObject(hfont);
@@ -233,7 +238,13 @@ HFONT FormatAndMetrics::HFont() {
 #define CLEARTYPE_QUALITY 5
 #endif
 
-static BYTE Win32MapFontQuality(int extraFontFlag) {
+namespace {
+
+FormatAndMetrics *FamFromFontID(void *fid) {
+	return static_cast<FormatAndMetrics *>(fid);
+}
+
+BYTE Win32MapFontQuality(int extraFontFlag) {
 	switch (extraFontFlag & SC_EFF_QUALITY_MASK) {
 
 		case SC_EFF_QUALITY_NON_ANTIALIASED:
@@ -251,7 +262,7 @@ static BYTE Win32MapFontQuality(int extraFontFlag) {
 }
 
 #if defined(USE_D2D)
-static D2D1_TEXT_ANTIALIAS_MODE DWriteMapFontQuality(int extraFontFlag) {
+D2D1_TEXT_ANTIALIAS_MODE DWriteMapFontQuality(int extraFontFlag) {
 	switch (extraFontFlag & SC_EFF_QUALITY_MASK) {
 
 		case SC_EFF_QUALITY_NON_ANTIALIASED:
@@ -269,12 +280,14 @@ static D2D1_TEXT_ANTIALIAS_MODE DWriteMapFontQuality(int extraFontFlag) {
 }
 #endif
 
+}
+
 static void SetLogFont(LOGFONTW &lf, const char *faceName, int characterSet, float size, int weight, bool italic, int extraFontFlag) {
 	lf = LOGFONTW();
 	// The negative is to allow for leading
-	lf.lfHeight = -(abs(static_cast<int>(size + 0.5)));
+	lf.lfHeight = -(abs(lround(size)));
 	lf.lfWeight = weight;
-	lf.lfItalic = static_cast<BYTE>(italic ? 1 : 0);
+	lf.lfItalic = italic ? 1 : 0;
 	lf.lfCharSet = static_cast<BYTE>(characterSet);
 	lf.lfQuality = Win32MapFontQuality(extraFontFlag);
 	UTF16FromUTF8(faceName, strlen(faceName)+1, lf.lfFaceName, LF_FACESIZE);
@@ -285,7 +298,7 @@ static void SetLogFont(LOGFONTW &lf, const char *faceName, int characterSet, flo
  * If one font is the same as another, its hash will be the same, but if the hash is the
  * same then they may still be different.
  */
-static int HashFont(const FontParameters &fp) {
+static int HashFont(const FontParameters &fp) noexcept {
 	return
 		static_cast<int>(fp.size) ^
 		(fp.characterSet << 10) ^
@@ -304,12 +317,12 @@ class FontCached : Font {
 	int technology;
 	int hash;
 	explicit FontCached(const FontParameters &fp);
-	~FontCached() override {}
 	bool SameAs(const FontParameters &fp);
 	void Release() override;
 
 	static FontCached *first;
 public:
+	~FontCached() override {}
 	static FontID FindOrCreate(const FontParameters &fp);
 	static void ReleaseId(FontID fid_);
 };
@@ -324,15 +337,15 @@ FontCached::FontCached(const FontParameters &fp) :
 	fid = 0;
 	if (technology == SCWIN_TECH_GDI) {
 		HFONT hfont = ::CreateFontIndirectW(&lf);
-		fid = static_cast<void *>(new FormatAndMetrics(hfont, fp.extraFontFlag, fp.characterSet));
+		fid = new FormatAndMetrics(hfont, fp.extraFontFlag, fp.characterSet);
 	} else {
 #if defined(USE_D2D)
 		IDWriteTextFormat *pTextFormat;
 		const int faceSize = 200;
 		WCHAR wszFace[faceSize];
 		UTF16FromUTF8(fp.faceName, strlen(fp.faceName)+1, wszFace, faceSize);
-		FLOAT fHeight = fp.size;
-		DWRITE_FONT_STYLE style = fp.italic ? DWRITE_FONT_STYLE_ITALIC : DWRITE_FONT_STYLE_NORMAL;
+		const FLOAT fHeight = fp.size;
+		const DWRITE_FONT_STYLE style = fp.italic ? DWRITE_FONT_STYLE_ITALIC : DWRITE_FONT_STYLE_NORMAL;
 		HRESULT hr = pIDWriteFactory->CreateTextFormat(wszFace, NULL,
 			static_cast<DWRITE_FONT_WEIGHT>(fp.weight),
 			style,
@@ -364,7 +377,7 @@ FontCached::FontCached(const FontParameters &fp) :
 				pTextLayout->Release();
 				pTextFormat->SetLineSpacing(DWRITE_LINE_SPACING_METHOD_UNIFORM, lineMetrics[0].height, lineMetrics[0].baseline);
 			}
-			fid = static_cast<void *>(new FormatAndMetrics(pTextFormat, fp.extraFontFlag, fp.characterSet, yAscent, yDescent, yInternalLeading));
+			fid = new FormatAndMetrics(pTextFormat, fp.extraFontFlag, fp.characterSet, yAscent, yDescent, yInternalLeading);
 		}
 #endif
 	}
@@ -375,7 +388,7 @@ bool FontCached::SameAs(const FontParameters &fp) {
 	if (
 		(size == fp.size) &&
 		(lf.lfWeight == fp.weight) &&
-		(lf.lfItalic == static_cast<BYTE>(fp.italic ? 1 : 0)) &&
+		(lf.lfItalic == (fp.italic ? 1 : 0)) &&
 		(lf.lfCharSet == fp.characterSet) &&
 		(lf.lfQuality == Win32MapFontQuality(fp.extraFontFlag)) &&
 		(technology == fp.technology)) {
@@ -387,8 +400,8 @@ bool FontCached::SameAs(const FontParameters &fp) {
 }
 
 void FontCached::Release() {
-	delete static_cast<FormatAndMetrics *>(fid);
-	fid = 0;
+	delete FamFromFontID(fid);
+	fid = nullptr;
 }
 
 FontID FontCached::FindOrCreate(const FontParameters &fp) {
@@ -469,7 +482,10 @@ class VarBuffer {
 	}
 	// Deleted so VarBuffer objects can not be copied.
 	VarBuffer(const VarBuffer &) = delete;
+	VarBuffer(VarBuffer &&) = delete;
 	VarBuffer &operator=(const VarBuffer &) = delete;
+	VarBuffer &operator=(VarBuffer &&) = delete;
+
 	~VarBuffer() {
 		if (buffer != bufferStandard) {
 			delete []buffer;
@@ -519,7 +535,10 @@ class SurfaceGDI : public Surface {
 	SurfaceGDI();
 	// Deleted so SurfaceGDI objects can not be copied.
 	SurfaceGDI(const SurfaceGDI &) = delete;
+	SurfaceGDI(SurfaceGDI &&) = delete;
 	SurfaceGDI &operator=(const SurfaceGDI &) = delete;
+	SurfaceGDI &operator=(SurfaceGDI &&) = delete;
+
 	~SurfaceGDI() override;
 
 	void Init(WindowID wid) override;
@@ -666,14 +685,14 @@ void SurfaceGDI::BrushColor(ColourDesired back) {
 		brushOld = 0;
 	}
 	// Only ever want pure, non-dithered brushes
-	ColourDesired colourNearest = ColourDesired(::GetNearestColor(hdc, back.AsLong()));
+	const ColourDesired colourNearest = ColourDesired(::GetNearestColor(hdc, back.AsLong()));
 	brush = ::CreateSolidBrush(colourNearest.AsLong());
 	brushOld = static_cast<HBRUSH>(::SelectObject(hdc, brush));
 }
 
 void SurfaceGDI::SetFont(Font &font_) {
 	if (font_.GetID() != font) {
-		FormatAndMetrics *pfm = static_cast<FormatAndMetrics *>(font_.GetID());
+		const FormatAndMetrics *pfm = FamFromFontID(font_.GetID());
 		PLATFORM_ASSERT(pfm->technology == SCWIN_TECH_GDI);
 		if (fontOld) {
 			::SelectObject(hdc, pfm->hfont);
@@ -721,7 +740,7 @@ void SurfaceGDI::RectangleDraw(PRectangle rc, ColourDesired fore, ColourDesired
 void SurfaceGDI::FillRectangle(PRectangle rc, ColourDesired back) {
 	// Using ExtTextOut rather than a FillRect ensures that no dithering occurs.
 	// There is no need to allocate a brush either.
-	RECT rcw = RectFromPRectangle(rc);
+	const RECT rcw = RectFromPRectangle(rc);
 	::SetBkColor(hdc, back.AsLong());
 	::ExtTextOut(hdc, rcw.left, rcw.top, ETO_OPAQUE, &rcw, TEXT(""), 0, NULL);
 }
@@ -732,7 +751,7 @@ void SurfaceGDI::FillRectangle(PRectangle rc, Surface &surfacePattern) {
 		br = ::CreatePatternBrush(static_cast<SurfaceGDI &>(surfacePattern).bitmap);
 	else	// Something is wrong so display in red
 		br = ::CreateSolidBrush(RGB(0xff, 0, 0));
-	RECT rcw = RectFromPRectangle(rc);
+	const RECT rcw = RectFromPRectangle(rc);
 	::FillRect(hdc, &rcw, br);
 	::DeleteObject(br);
 }
@@ -747,15 +766,17 @@ void SurfaceGDI::RoundedRectangle(PRectangle rc, ColourDesired fore, ColourDesir
 		8, 8);
 }
 
+namespace {
+
 // Plot a point into a DWORD buffer symmetrically to all 4 quadrants
-static void AllFour(DWORD *pixels, int width, int height, int x, int y, DWORD val) {
+void AllFour(DWORD *pixels, int width, int height, int x, int y, DWORD val) {
 	pixels[y*width+x] = val;
 	pixels[y*width+width-1-x] = val;
 	pixels[(height-1-y)*width+x] = val;
 	pixels[(height-1-y)*width+width-1-x] = val;
 }
 
-static DWORD dwordFromBGRA(byte b, byte g, byte r, byte a) {
+DWORD dwordFromBGRA(byte b, byte g, byte r, byte a) {
 	union {
 		byte pixVal[4];
 		DWORD val;
@@ -767,35 +788,38 @@ static DWORD dwordFromBGRA(byte b, byte g, byte r, byte a) {
 	return converter.val;
 }
 
+DWORD dwordMultiplied(ColourDesired colour, unsigned int alpha) {
+	return dwordFromBGRA(
+		static_cast<byte>(colour.GetBlue() * alpha / 255),
+		static_cast<byte>(colour.GetGreen() * alpha / 255),
+		static_cast<byte>(colour.GetRed() * alpha / 255),
+		static_cast<byte>(alpha));
+}
+
+}
+
 void SurfaceGDI::AlphaRectangle(PRectangle rc, int cornerSize, ColourDesired fill, int alphaFill,
 		ColourDesired outline, int alphaOutline, int /* flags*/ ) {
 	const RECT rcw = RectFromPRectangle(rc);
 	if (rc.Width() > 0) {
 		HDC hMemDC = ::CreateCompatibleDC(hdc);
-		int width = static_cast<int>(rc.Width());
-		int height = static_cast<int>(rc.Height());
+		const int width = rcw.right - rcw.left;
+		const int height = rcw.bottom - rcw.top;
 		// Ensure not distorted too much by corners when small
 		cornerSize = std::min(cornerSize, (std::min(width, height) / 2) - 2);
 		const BITMAPINFO bpih = {{sizeof(BITMAPINFOHEADER), width, height, 1, 32, BI_RGB, 0, 0, 0, 0, 0},
 			{{0, 0, 0, 0}}};
-		void *image = 0;
+		void *image = nullptr;
 		HBITMAP hbmMem = CreateDIBSection(hMemDC, &bpih,
 			DIB_RGB_COLORS, &image, NULL, 0);
 
 		if (hbmMem) {
 			HBITMAP hbmOld = SelectBitmap(hMemDC, hbmMem);
 
-			DWORD valEmpty = dwordFromBGRA(0,0,0,0);
-			DWORD valFill = dwordFromBGRA(
-				static_cast<byte>(fill.GetBlue() * alphaFill / 255),
-				static_cast<byte>(fill.GetGreen() * alphaFill / 255),
-				static_cast<byte>(fill.GetRed() * alphaFill / 255),
-				static_cast<byte>(alphaFill));
-			DWORD valOutline = dwordFromBGRA(
-				static_cast<byte>(outline.GetBlue() * alphaFill / 255),
-				static_cast<byte>(outline.GetGreen() * alphaFill / 255),
-				static_cast<byte>(outline.GetRed() * alphaFill / 255),
-				static_cast<byte>(alphaOutline));
+			const DWORD valEmpty = dwordFromBGRA(0,0,0,0);
+			const DWORD valFill = dwordMultiplied(fill, alphaFill);
+			const DWORD valOutline = dwordMultiplied(outline, alphaOutline);
+
 			DWORD *pixels = static_cast<DWORD *>(image);
 			for (int y=0; y<height; y++) {
 				for (int x=0; x<width; x++) {
@@ -815,7 +839,7 @@ void SurfaceGDI::AlphaRectangle(PRectangle rc, int cornerSize, ColourDesired fil
 				AllFour(pixels, width, height, x, cornerSize-x, valOutline);
 			}
 
-			BLENDFUNCTION merge = { AC_SRC_OVER, 0, 255, AC_SRC_ALPHA };
+			const BLENDFUNCTION merge = { AC_SRC_OVER, 0, 255, AC_SRC_ALPHA };
 
 			AlphaBlend(hdc, rcw.left, rcw.top, width, height, hMemDC, 0, 0, width, height, merge);
 
@@ -841,25 +865,25 @@ void SurfaceGDI::DrawRGBAImage(PRectangle rc, int width, int height, const unsig
 
 		const BITMAPINFO bpih = {{sizeof(BITMAPINFOHEADER), width, height, 1, 32, BI_RGB, 0, 0, 0, 0, 0},
 			{{0, 0, 0, 0}}};
-		unsigned char *image = 0;
+		void *image = nullptr;
 		HBITMAP hbmMem = CreateDIBSection(hMemDC, &bpih,
-			DIB_RGB_COLORS, reinterpret_cast<void **>(&image), NULL, 0);
+			DIB_RGB_COLORS, &image, NULL, 0);
 		if (hbmMem) {
 			HBITMAP hbmOld = SelectBitmap(hMemDC, hbmMem);
 
 			for (int y=height-1; y>=0; y--) {
 				for (int x=0; x<width; x++) {
-					unsigned char *pixel = image + (y*width+x) * 4;
+					unsigned char *pixel = static_cast<unsigned char *>(image) + (y*width+x) * 4;
 					const unsigned char alpha = pixelsImage[3];
 					// Input is RGBA, output is BGRA with premultiplied alpha
 					pixel[2] = static_cast<unsigned char>((*pixelsImage++) * alpha / 255);
 					pixel[1] = static_cast<unsigned char>((*pixelsImage++) * alpha / 255);
 					pixel[0] = static_cast<unsigned char>((*pixelsImage++) * alpha / 255);
-					pixel[3] = static_cast<unsigned char>(*pixelsImage++);
+					pixel[3] = *pixelsImage++;
 				}
 			}
 
-			BLENDFUNCTION merge = { AC_SRC_OVER, 0, 255, AC_SRC_ALPHA };
+			const BLENDFUNCTION merge = { AC_SRC_OVER, 0, 255, AC_SRC_ALPHA };
 
 			AlphaBlend(hdc, static_cast<int>(rc.left), static_cast<int>(rc.top),
 				static_cast<int>(rc.Width()), static_cast<int>(rc.Height()), hMemDC, 0, 0, width, height, merge);
@@ -1078,7 +1102,9 @@ class SurfaceD2D : public Surface {
 	SurfaceD2D();
 	// Deleted so SurfaceD2D objects can not be copied.
 	SurfaceD2D(const SurfaceD2D &) = delete;
+	SurfaceD2D(SurfaceD2D &&) = delete;
 	SurfaceD2D &operator=(const SurfaceD2D &) = delete;
+	SurfaceD2D &operator=(SurfaceD2D &&) = delete;
 	virtual ~SurfaceD2D() override;
 
 	void SetScale();
@@ -1209,7 +1235,7 @@ void SurfaceD2D::InitPixMap(int width, int height, Surface *surface_, WindowID)
 	SetScale();
 	SurfaceD2D *psurfOther = static_cast<SurfaceD2D *>(surface_);
 	ID2D1BitmapRenderTarget *pCompatibleRenderTarget = NULL;
-	D2D1_SIZE_F desiredSize = D2D1::SizeF(static_cast<float>(width), static_cast<float>(height));
+	const D2D1_SIZE_F desiredSize = D2D1::SizeF(static_cast<float>(width), static_cast<float>(height));
 	D2D1_PIXEL_FORMAT desiredFormat;
 #ifdef __MINGW32__
 	desiredFormat.format = DXGI_FORMAT_UNKNOWN;
@@ -1252,7 +1278,7 @@ void SurfaceD2D::D2DPenColour(ColourDesired fore, int alpha) {
 }
 
 void SurfaceD2D::SetFont(Font &font_) {
-	FormatAndMetrics *pfm = static_cast<FormatAndMetrics *>(font_.GetID());
+	const FormatAndMetrics *pfm = FamFromFontID(font_.GetID());
 	PLATFORM_ASSERT(pfm->technology == SCWIN_TECH_DIRECTWRITE);
 	pTextFormat = pfm->pTextFormat;
 	yAscent = pfm->yAscent;
@@ -1297,11 +1323,6 @@ static int Delta(int difference) {
 		return 0;
 }
 
-// Round to integer, with halfway cases rounding down.
-static float RoundFloat(float f) {
-	return std::floor(f+0.5f);
-}
-
 void SurfaceD2D::LineTo(int x_, int y_) {
 	if (pRenderTarget) {
 		const int xDiff = x_ - x;
@@ -1316,7 +1337,7 @@ void SurfaceD2D::LineTo(int x_, int y_) {
 			const int yEnd = y_ - yDelta;
 			const int top = std::min(y, yEnd);
 			const int height = abs(y - yEnd) + 1;
-			D2D1_RECT_F rectangle1 = D2D1::RectF(static_cast<float>(left), static_cast<float>(top),
+			const D2D1_RECT_F rectangle1 = D2D1::RectF(static_cast<float>(left), static_cast<float>(top),
 				static_cast<float>(left+width), static_cast<float>(top+height));
 			pRenderTarget->FillRectangle(&rectangle1, pBrush);
 		} else if ((abs(xDiff) == abs(yDiff))) {
@@ -1344,7 +1365,7 @@ void SurfaceD2D::Polygon(Point *pts, int npts, ColourDesired fore, ColourDesired
 			hr = geometry->Open(&sink);
 			if (SUCCEEDED(hr)) {
 				sink->BeginFigure(D2D1::Point2F(pts[0].x + 0.5f, pts[0].y + 0.5f), D2D1_FIGURE_BEGIN_FILLED);
-				for (size_t i=1; i<static_cast<size_t>(npts); i++) {
+				for (int i=1; i<npts; i++) {
 					sink->AddLine(D2D1::Point2F(pts[i].x + 0.5f, pts[i].y + 0.5f));
 				}
 				sink->EndFigure(D2D1_FIGURE_END_CLOSED);
@@ -1364,7 +1385,7 @@ void SurfaceD2D::Polygon(Point *pts, int npts, ColourDesired fore, ColourDesired
 
 void SurfaceD2D::RectangleDraw(PRectangle rc, ColourDesired fore, ColourDesired back) {
 	if (pRenderTarget) {
-		D2D1_RECT_F rectangle1 = D2D1::RectF(RoundFloat(rc.left) + 0.5f, rc.top+0.5f, RoundFloat(rc.right) - 0.5f, rc.bottom-0.5f);
+		const D2D1_RECT_F rectangle1 = D2D1::RectF(round(rc.left) + 0.5f, rc.top+0.5f, round(rc.right) - 0.5f, rc.bottom-0.5f);
 		D2DPenColour(back);
 		pRenderTarget->FillRectangle(&rectangle1, pBrush);
 		D2DPenColour(fore);
@@ -1375,7 +1396,7 @@ void SurfaceD2D::RectangleDraw(PRectangle rc, ColourDesired fore, ColourDesired
 void SurfaceD2D::FillRectangle(PRectangle rc, ColourDesired back) {
 	if (pRenderTarget) {
 		D2DPenColour(back);
-        D2D1_RECT_F rectangle1 = D2D1::RectF(RoundFloat(rc.left), rc.top, RoundFloat(rc.right), rc.bottom);
+        const D2D1_RECT_F rectangle1 = D2D1::RectF(round(rc.left), rc.top, round(rc.right), rc.bottom);
         pRenderTarget->FillRectangle(&rectangle1, pBrush);
 	}
 }
@@ -1389,7 +1410,7 @@ void SurfaceD2D::FillRectangle(PRectangle rc, Surface &surfacePattern) {
 	HRESULT hr = pCompatibleRenderTarget->GetBitmap(&pBitmap);
 	if (SUCCEEDED(hr)) {
 		ID2D1BitmapBrush *pBitmapBrush = NULL;
-		D2D1_BITMAP_BRUSH_PROPERTIES brushProperties =
+		const D2D1_BITMAP_BRUSH_PROPERTIES brushProperties =
 	        D2D1::BitmapBrushProperties(D2D1_EXTEND_MODE_WRAP, D2D1_EXTEND_MODE_WRAP,
 			D2D1_BITMAP_INTERPOLATION_MODE_NEAREST_NEIGHBOR);
 		// Create the bitmap brush.
@@ -1425,23 +1446,23 @@ void SurfaceD2D::AlphaRectangle(PRectangle rc, int cornerSize, ColourDesired fil
 	if (pRenderTarget) {
 		if (cornerSize == 0) {
 			// When corner size is zero, draw square rectangle to prevent blurry pixels at corners
-			D2D1_RECT_F rectFill = D2D1::RectF(RoundFloat(rc.left) + 1.0f, rc.top + 1.0f, RoundFloat(rc.right) - 1.0f, rc.bottom - 1.0f);
+			const D2D1_RECT_F rectFill = D2D1::RectF(round(rc.left) + 1.0f, rc.top + 1.0f, round(rc.right) - 1.0f, rc.bottom - 1.0f);
 			D2DPenColour(fill, alphaFill);
 			pRenderTarget->FillRectangle(rectFill, pBrush);
 
-			D2D1_RECT_F rectOutline = D2D1::RectF(RoundFloat(rc.left) + 0.5f, rc.top + 0.5f, RoundFloat(rc.right) - 0.5f, rc.bottom - 0.5f);
+			const D2D1_RECT_F rectOutline = D2D1::RectF(round(rc.left) + 0.5f, rc.top + 0.5f, round(rc.right) - 0.5f, rc.bottom - 0.5f);
 			D2DPenColour(outline, alphaOutline);
 			pRenderTarget->DrawRectangle(rectOutline, pBrush);
 		} else {
 			const float cornerSizeF = static_cast<float>(cornerSize);
 			D2D1_ROUNDED_RECT roundedRectFill = {
-				D2D1::RectF(RoundFloat(rc.left) + 1.0f, rc.top + 1.0f, RoundFloat(rc.right) - 1.0f, rc.bottom - 1.0f),
+				D2D1::RectF(round(rc.left) + 1.0f, rc.top + 1.0f, round(rc.right) - 1.0f, rc.bottom - 1.0f),
 				cornerSizeF, cornerSizeF};
 			D2DPenColour(fill, alphaFill);
 			pRenderTarget->FillRoundedRectangle(roundedRectFill, pBrush);
 
 			D2D1_ROUNDED_RECT roundedRect = {
-				D2D1::RectF(RoundFloat(rc.left) + 0.5f, rc.top + 0.5f, RoundFloat(rc.right) - 0.5f, rc.bottom - 0.5f),
+				D2D1::RectF(round(rc.left) + 0.5f, rc.top + 0.5f, round(rc.right) - 0.5f, rc.bottom - 0.5f),
 				cornerSizeF, cornerSizeF};
 			D2DPenColour(outline, alphaOutline);
 			pRenderTarget->DrawRoundedRectangle(roundedRect, pBrush);
@@ -1472,7 +1493,7 @@ void SurfaceD2D::DrawRGBAImage(PRectangle rc, int width, int height, const unsig
 		}
 
 		ID2D1Bitmap *bitmap = 0;
-		D2D1_SIZE_U size = D2D1::SizeU(width, height);
+		const D2D1_SIZE_U size = D2D1::SizeU(width, height);
 		D2D1_BITMAP_PROPERTIES props = {{DXGI_FORMAT_B8G8R8A8_UNORM,
 		    D2D1_ALPHA_MODE_PREMULTIPLIED}, 72.0, 72.0};
 		const HRESULT hr = pRenderTarget->CreateBitmap(size, &image[0],
@@ -1487,7 +1508,7 @@ void SurfaceD2D::DrawRGBAImage(PRectangle rc, int width, int height, const unsig
 
 void SurfaceD2D::Ellipse(PRectangle rc, ColourDesired fore, ColourDesired back) {
 	if (pRenderTarget) {
-		FLOAT radius = rc.Width() / 2.0f;
+		const FLOAT radius = rc.Width() / 2.0f;
 		D2D1_ELLIPSE ellipse = {
 			D2D1::Point2F((rc.left + rc.right) / 2.0f, (rc.top + rc.bottom) / 2.0f),
 			radius,radius};
@@ -1811,11 +1832,11 @@ void Window::SetPositionRelative(PRectangle rc, Window relativeTo) {
 		::ClientToScreen(static_cast<HWND>(relativeTo.GetID()), &ptOther);
 		rc.Move(static_cast<XYPOSITION>(ptOther.x), static_cast<XYPOSITION>(ptOther.y));
 
-		RECT rcMonitor = RectFromPRectangle(rc);
+		const RECT rcMonitor = RectFromPRectangle(rc);
 
 		HMONITOR hMonitor = MonitorFromRect(&rcMonitor, MONITOR_DEFAULTTONEAREST);
 		// If hMonitor is NULL, that's just the main screen anyways.
-		RECT rcWork = RectFromMonitor(hMonitor);
+		const RECT rcWork = RectFromMonitor(hMonitor);
 
 		if (rcWork.left < rcWork.right) {
 			// Now clamp our desired rectangle to fit inside the work area
@@ -1854,11 +1875,11 @@ void Window::InvalidateAll() {
 }
 
 void Window::InvalidateRectangle(PRectangle rc) {
-	RECT rcw = RectFromPRectangle(rc);
+	const RECT rcw = RectFromPRectangle(rc);
 	::InvalidateRect(static_cast<HWND>(wid), &rcw, FALSE);
 }
 
-static LRESULT Window_SendMessage(Window *w, UINT msg, WPARAM wParam=0, LPARAM lParam=0) {
+static LRESULT Window_SendMessage(const Window *w, UINT msg, WPARAM wParam=0, LPARAM lParam=0) {
 	return ::SendMessage(static_cast<HWND>(w->GetID()), msg, wParam, lParam);
 }
 
@@ -1892,7 +1913,7 @@ static HCURSOR GetReverseArrowCursor() {
 				FlipBitmap(info.hbmMask, bmp.bmWidth, bmp.bmHeight);
 				if (info.hbmColor != NULL)
 					FlipBitmap(info.hbmColor, bmp.bmWidth, bmp.bmHeight);
-				info.xHotspot = static_cast<DWORD>(bmp.bmWidth) - 1 - info.xHotspot;
+				info.xHotspot = bmp.bmWidth - 1 - info.xHotspot;
 
 				reverseArrowCursor = ::CreateIconIndirect(&info);
 				if (reverseArrowCursor != NULL)
@@ -1941,12 +1962,12 @@ void Window::SetCursor(Cursor curs) {
 /* Returns rectangle of monitor pt is on, both rect and pt are in Window's
    coordinates */
 PRectangle Window::GetMonitorRect(Point pt) {
-	PRectangle rcPosition = GetPosition();
+	const PRectangle rcPosition = GetPosition();
 	POINT ptDesktop = {static_cast<LONG>(pt.x + rcPosition.left),
 		static_cast<LONG>(pt.y + rcPosition.top)};
 	HMONITOR hMonitor = MonitorFromPoint(ptDesktop, MONITOR_DEFAULTTONEAREST);
 
-	RECT rcWork = RectFromMonitor(hMonitor);
+	const RECT rcWork = RectFromMonitor(hMonitor);
 	if (rcWork.left < rcWork.right) {
 		PRectangle rcMonitor(
 			rcWork.left - rcPosition.left,
@@ -1970,18 +1991,13 @@ class LineToItem {
 	std::vector<ListItemData> data;
 
 public:
-	LineToItem() {
-	}
-	~LineToItem() {
-		Clear();
-	}
 	void Clear() {
 		words.clear();
 		data.clear();
 	}
 
-	ListItemData Get(int index) const {
-		if (index >= 0 && index < static_cast<int>(data.size())) {
+	ListItemData Get(size_t index) const {
+		if (index < data.size()) {
 			return data[index];
 		} else {
 			ListItemData missing = {"", -1};
@@ -2086,7 +2102,7 @@ class ListBoxX : public ListBox {
 	void RegisterImage(int type, const char *xpm_data) override;
 	void RegisterRGBAImage(int type, int width, int height, const unsigned char *pixelsImage) override;
 	void ClearRegisteredImages() override;
-	virtual void SetDelegate(IListBoxDelegate *lbDelegate) override;
+	void SetDelegate(IListBoxDelegate *lbDelegate) override;
 	void SetList(const char *list, char separator, char typesep) override;
 	void Draw(DRAWITEMSTRUCT *pDrawItem);
 	LRESULT WndProc(HWND hWnd, UINT iMessage, WPARAM wParam, LPARAM lParam);
@@ -2194,7 +2210,7 @@ PRectangle ListBoxX::GetDesiredRect() {
 }
 
 int ListBoxX::TextOffset() const {
-	int pixWidth = images.GetWidth();
+	const int pixWidth = images.GetWidth();
 	return static_cast<int>(pixWidth == 0 ? ItemInset.x : ItemInset.x + pixWidth + (ImageInset.x * 2));
 }
 
@@ -2278,9 +2294,9 @@ void ListBoxX::Draw(DRAWITEMSTRUCT *pDrawItem) {
 		}
 
 		const ListItemData item = lti.Get(pDrawItem->itemID);
-		int pixId = item.pixId;
+		const int pixId = item.pixId;
 		const char *text = item.text;
-		int len = static_cast<int>(strlen(text));
+		const int len = static_cast<int>(strlen(text));
 
 		RECT rcText = rcBox;
 		::InsetRect(&rcText, static_cast<int>(TextInset.x), static_cast<int>(TextInset.y));
@@ -2299,14 +2315,14 @@ void ListBoxX::Draw(DRAWITEMSTRUCT *pDrawItem) {
 			if (technology == SCWIN_TECH_GDI) {
 				surfaceItem->Init(pDrawItem->hDC, pDrawItem->hwndItem);
 				const long left = pDrawItem->rcItem.left + static_cast<int>(ItemInset.x + ImageInset.x);
-				PRectangle rcImage = PRectangle::FromInts(left, pDrawItem->rcItem.top,
+				const PRectangle rcImage = PRectangle::FromInts(left, pDrawItem->rcItem.top,
 					left + images.GetWidth(), pDrawItem->rcItem.bottom);
 				surfaceItem->DrawRGBAImage(rcImage,
 					pimage->GetWidth(), pimage->GetHeight(), pimage->Pixels());
 				::SetTextAlign(pDrawItem->hDC, TA_TOP);
 			} else {
 #if defined(USE_D2D)
-				D2D1_RENDER_TARGET_PROPERTIES props = D2D1::RenderTargetProperties(
+				const D2D1_RENDER_TARGET_PROPERTIES props = D2D1::RenderTargetProperties(
 					D2D1_RENDER_TARGET_TYPE_DEFAULT,
 					D2D1::PixelFormat(
 						DXGI_FORMAT_B8G8R8A8_UNORM,
@@ -2326,7 +2342,7 @@ void ListBoxX::Draw(DRAWITEMSTRUCT *pDrawItem) {
 						surfaceItem->Init(pDCRT, pDrawItem->hwndItem);
 						pDCRT->BeginDraw();
 						const long left = pDrawItem->rcItem.left + static_cast<long>(ItemInset.x + ImageInset.x);
-						PRectangle rcImage = PRectangle::FromInts(left, pDrawItem->rcItem.top,
+						const PRectangle rcImage = PRectangle::FromInts(left, pDrawItem->rcItem.top,
 							left + images.GetWidth(), pDrawItem->rcItem.bottom);
 						surfaceItem->DrawRGBAImage(rcImage,
 							pimage->GetWidth(), pimage->GetHeight(), pimage->Pixels());
@@ -2390,7 +2406,7 @@ void ListBoxX::SetList(const char *list, char separator, char typesep) {
 	}
 
 	// Finally populate the listbox itself with the correct number of items
-	int count = lti.Count();
+	const int count = lti.Count();
 	::SendMessage(lb, LB_INITSTORAGE, count, 0);
 	for (int j=0; j<count; j++) {
 		::SendMessage(lb, LB_ADDSTRING, 0, j+1);
@@ -2441,20 +2457,6 @@ void ListBoxX::SetRedraw(bool on) {
 		::InvalidateRect(lb, NULL, TRUE);
 }
 
-static XYPOSITION XYMinimum(XYPOSITION a, XYPOSITION b) {
-	if (a < b)
-		return a;
-	else
-		return b;
-}
-
-static XYPOSITION XYMaximum(XYPOSITION a, XYPOSITION b) {
-	if (a > b)
-		return a;
-	else
-		return b;
-}
-
 void ListBoxX::ResizeToCursor() {
 	PRectangle rc = GetPosition();
 	POINT ptw;
@@ -2494,13 +2496,13 @@ void ListBoxX::ResizeToCursor() {
 			break;
 	}
 
-	POINT ptMin = MinTrackSize();
-	POINT ptMax = MaxTrackSize();
+	const POINT ptMin = MinTrackSize();
+	const POINT ptMax = MaxTrackSize();
 	// We don't allow the left edge to move at present, but just in case
-	rc.left = XYMaximum(XYMinimum(rc.left, rcPreSize.right - ptMin.x), rcPreSize.right - ptMax.x);
-	rc.top = XYMaximum(XYMinimum(rc.top, rcPreSize.bottom - ptMin.y), rcPreSize.bottom - ptMax.y);
-	rc.right = XYMaximum(XYMinimum(rc.right, rcPreSize.left + ptMax.x), rcPreSize.left + ptMin.x);
-	rc.bottom = XYMaximum(XYMinimum(rc.bottom, rcPreSize.top + ptMax.y), rcPreSize.top + ptMin.y);
+	rc.left = std::clamp(rc.left, rcPreSize.right - ptMax.x, rcPreSize.right - ptMin.x);
+	rc.top = std::clamp(rc.top, rcPreSize.bottom - ptMax.y, rcPreSize.bottom - ptMin.y);
+	rc.right = std::clamp(rc.right, rcPreSize.left + ptMin.x, rcPreSize.left + ptMax.x);
+	rc.bottom = std::clamp(rc.bottom, rcPreSize.top + ptMin.y, rcPreSize.top + ptMax.y);
 
 	SetPosition(rc);
 }
@@ -2620,7 +2622,7 @@ void ListBoxX::CentreItem(int n) {
 		const int visible = extent.y/ItemHeight();
 		if (visible < Length()) {
 			const LRESULT top = ::SendMessage(lb, LB_GETTOPINDEX, 0, 0);
-			int half = (visible - 1) / 2;
+			const int half = (visible - 1) / 2;
 			if (n > (top + half))
 				::SendMessage(lb, LB_SETTOPINDEX, n - half , 0);
 		}
@@ -2629,7 +2631,7 @@ void ListBoxX::CentreItem(int n) {
 
 // Performs a double-buffered paint operation to avoid flicker
 void ListBoxX::Paint(HDC hDC) {
-	POINT extent = GetClientExtent();
+	const POINT extent = GetClientExtent();
 	HBITMAP hBitmap = ::CreateCompatibleBitmap(hDC, extent.x, extent.y);
 	HDC bitmapDC = ::CreateCompatibleDC(hDC);
 	HBITMAP hBitmapOld = SelectBitmap(bitmapDC, hBitmap);
@@ -2672,7 +2674,7 @@ LRESULT PASCAL ListBoxX::ControlWndProc(HWND hWnd, UINT iMessage, WPARAM wParam,
 				// We must take control of selection to prevent the ListBox activating
 				// the popup
 				const LRESULT lResult = ::SendMessage(hWnd, LB_ITEMFROMPOINT, 0, lParam);
-				int item = LOWORD(lResult);
+				const int item = LOWORD(lResult);
 				if (HIWORD(lResult) == 0 && item >= 0) {
 					::SendMessage(hWnd, LB_SETCURSEL, item, 0);
 					ListBoxX *lbx = static_cast<ListBoxX *>(PointerFromWindow(::GetParent(hWnd)));
diff --git a/src/Edit.c b/src/Edit.c
index dec5e407c..383a2cee8 100644
--- a/src/Edit.c
+++ b/src/Edit.c
@@ -347,24 +347,27 @@ void __fastcall _ClearTextBuffer(HWND hwnd)
 {
   SendMessage(hwnd, SCI_CANCEL, 0, 0);
 
-  if (SendMessage(hwnd, SCI_GETREADONLY, 0, 0)) { SendMessage(hwnd, SCI_SETREADONLY, false, 0); }
+  IgnoreNotifyChangeEvent();
+  
+  if (SciCall_GetReadOnly()) { SciCall_SetReadOnly(false); }
 
   UndoRedoActionMap(-1, NULL); 
-
   SciCall_SetUndoCollection(false);
 
-  SendMessage(hwnd, SCI_CLEARALL, 0, 0);
-  SendMessage(hwnd, SCI_MARKERDELETEALL, (WPARAM)MARKER_NP3_BOOKMARK, 0);
-
   EditClearAllOccurrenceMarkers(hwnd, 0, -1);
   if (EditToggleView(g_hwndEdit, false)) {
     EditToggleView(g_hwndEdit, true);
   }
 
+  SendMessage(hwnd, SCI_CLEARALL, 0, 0);
+  SendMessage(hwnd, SCI_MARKERDELETEALL, (WPARAM)MARKER_NP3_BOOKMARK, 0);
+
   SciCall_SetUndoCollection(true);
 
   SendMessage(hwnd, SCI_SETSCROLLWIDTH, 1, 0);
   SendMessage(hwnd, SCI_SETXOFFSET, 0, 0);
+
+  ObserveNotifyChangeEvent();
 }
 
 
@@ -7972,16 +7975,10 @@ int FileVars_GetEncoding(LPFILEVARS lpfv) {
 #define FOLD_CHILDREN SCMOD_CTRL
 #define FOLD_SIBLINGS SCMOD_SHIFT
 
-bool __stdcall FoldToggleNode(DocLn ln, FOLD_ACTION action)
+bool __forceinline _FoldToggleNode(DocLn ln, FOLD_ACTION action)
 {
-  const bool fExpanded = SciCall_GetFoldExpanded(ln);
-
-  if ((action == FOLD && fExpanded) || (action == EXPAND && !fExpanded))
-  {
-    SciCall_ToggleFold(ln);
-    return true;
-  }
-  else if (action == SNIFF)
+  bool const fExpanded = SciCall_GetFoldExpanded(ln);
+  if ((action == SNIFF) || ((action == FOLD) && fExpanded) || ((action == EXPAND) && !fExpanded))
   {
     SciCall_ToggleFold(ln);
     return true;
@@ -8020,48 +8017,75 @@ void __stdcall EditFoldPerformAction(DocLn ln, int mode, FOLD_ACTION action)
       if (lv < lvStop || (lv == lvStop && fHeader && ln != lnNode))
         return;
       else if (fHeader && (lv == lvNode || (lv > lvNode && mode & FOLD_CHILDREN)))
-        FoldToggleNode(ln, action);
+        _FoldToggleNode(ln, action);
     }
   }
   else {
-    FoldToggleNode(ln, action);
+    _FoldToggleNode(ln, action);
   }
 }
 
 
-void EditFoldToggleAll(FOLD_ACTION action)
+void EditToggleFolds(FOLD_ACTION action, bool bForceAll)
 {
-  static FOLD_ACTION sLastAction = EXPAND;
+  static FOLD_ACTION sbLastSniffAllAction = EXPAND;
 
-  bool fToggled = false;
-
-  DocLn lnTotal = SciCall_GetLineCount();
+  bool bAllLines = true;
+  DocLn iStartLine = 0;
+  DocLn iEndLine = SciCall_GetLineCount() - 1;
 
-  if (action == SNIFF)
+  if (!bForceAll && !SciCall_IsSelectionEmpty())
   {
-    int cntFolded = 0;
-    int cntExpanded = 0;
-    for (int ln = 0; ln < lnTotal; ++ln)
-    {
-      if (SciCall_GetFoldLevel(ln) & SC_FOLDLEVELHEADERFLAG)
+    DocLn const iBegLn = SciCall_LineFromPosition(SciCall_GetSelectionStart());
+    DocLn const iEndLn = SciCall_LineFromPosition(SciCall_GetSelectionEnd());
+    // selection range must span at least two lines
+    if (iBegLn != iEndLn) {
+      iStartLine = iBegLn;
+      iEndLine = iEndLn;
+      bAllLines = false;
+    }
+  }
+
+  bool fToggled = false;
+
+  if (bAllLines) {
+    if (action == SNIFF) {
+      // determine majority to find action for all
+      int cntFolded = 0;
+      int cntExpanded = 0;
+      for (DocLn ln = iStartLine; ln <= iEndLine; ++ln)
       {
-        if (SciCall_GetFoldExpanded(ln))
-          ++cntExpanded;
-        else
-          ++cntFolded;
+        if (SciCall_GetFoldLevel(ln) & SC_FOLDLEVELHEADERFLAG)
+        {
+          if (SciCall_GetLastChild(ln, -1) != ln)
+          {
+            if (SciCall_GetFoldExpanded(ln))
+              ++cntExpanded;
+            else
+              ++cntFolded;
+          }
+        }
       }
+      if (cntFolded == cntExpanded) {
+        action = (sbLastSniffAllAction == FOLD) ? EXPAND : FOLD;
+      }
+      else {
+        action = (cntFolded < cntExpanded) ? FOLD : EXPAND;
+      }
+      sbLastSniffAllAction = action;
     }
-    if (cntFolded == cntExpanded)
-      action = (sLastAction == FOLD) ? EXPAND : FOLD;
-    else
-      action = (cntFolded < cntExpanded) ? FOLD : EXPAND;
-  }
 
-  for (int ln = 0; ln < lnTotal; ++ln)
+    SciCall_FoldAll(action);
+    fToggled = true;
+  }
+  else // in selection
   {
-    if (SciCall_GetFoldLevel(ln) & SC_FOLDLEVELHEADERFLAG)
+    for (DocLn ln = iStartLine; ln <= iEndLine; ++ln)
     {
-      if (FoldToggleNode(ln, action)) { fToggled = true; }
+      if (SciCall_GetFoldLevel(ln) & SC_FOLDLEVELHEADERFLAG)
+      {
+        if (_FoldToggleNode(ln, action)) { fToggled = !fToggled ? true : false; }
+      }
     }
   }
   if (fToggled) { SciCall_ScrollCaret(); }
@@ -8146,7 +8170,7 @@ void EditFoldAltArrow(FOLD_MOVE move, FOLD_ACTION action)
     if (SciCall_GetFoldLevel(ln) & SC_FOLDLEVELHEADERFLAG)
     {
       if (action != SNIFF) {
-        FoldToggleNode(ln, action);
+        _FoldToggleNode(ln, action);
       }
     }
   }
diff --git a/src/Edit.h b/src/Edit.h
index f4484a6ec..15eb5b0af 100644
--- a/src/Edit.h
+++ b/src/Edit.h
@@ -157,9 +157,9 @@ int  FileVars_GetEncoding(LPFILEVARS);
 //  Folding Functions
 //
 typedef enum {
-  EXPAND = 1,
-  SNIFF = 0,
-  FOLD = -1
+  FOLD = SC_FOLDACTION_CONTRACT,
+  EXPAND = SC_FOLDACTION_EXPAND,
+  SNIFF = SC_FOLDACTION_TOGGLE
 } FOLD_ACTION;
 
 typedef enum {
@@ -168,7 +168,7 @@ typedef enum {
   DOWN = 1
 } FOLD_MOVE;
 
-void EditFoldToggleAll(FOLD_ACTION);
+void EditToggleFolds(FOLD_ACTION,bool);
 void EditFoldClick(DocLn, int);
 void EditFoldAltArrow(FOLD_MOVE, FOLD_ACTION);
 
diff --git a/src/Notepad3.c b/src/Notepad3.c
index 177213ec1..fe150dc55 100644
--- a/src/Notepad3.c
+++ b/src/Notepad3.c
@@ -2448,7 +2448,7 @@ void MsgInitMenu(HWND hwnd,WPARAM wParam,LPARAM lParam)
 
   EnableCmd(hmenu, CMD_CTRLENTER, !ro);
   EnableCmd(hmenu, IDM_EDIT_INSERT_TAG, !ro);
-  EnableCmd(hmenu,IDM_EDIT_INSERT_ENCODING, *Encoding_GetParseNames(Encoding_Current(CPI_GET) && !ro));
+  EnableCmd(hmenu, IDM_EDIT_INSERT_ENCODING, (Encoding_GetParseNames(Encoding_Current(CPI_GET)) != NULL) && !ro);
 
   EnableCmd(hmenu,IDM_EDIT_INSERT_SHORTDATE,!ro);
   EnableCmd(hmenu,IDM_EDIT_INSERT_LONGDATE,!ro);
@@ -4375,13 +4375,13 @@ LRESULT MsgCommand(HWND hwnd, WPARAM wParam, LPARAM lParam)
     case IDM_VIEW_FOLDING:
       g_bShowCodeFolding = (g_bShowCodeFolding) ? false : true;
       Style_SetFolding(g_hwndEdit, g_bShowCodeFolding);
-      if (!g_bShowCodeFolding) { EditFoldToggleAll(EXPAND); }
+      if (!g_bShowCodeFolding) { EditToggleFolds(EXPAND, true); }
       UpdateToolbar();
       break;
 
 
     case IDM_VIEW_TOGGLEFOLDS:
-      EditFoldToggleAll(SNIFF);
+      EditToggleFolds(SNIFF, false);
       break;
 
 
@@ -7243,7 +7243,7 @@ void UpdateToolbar()
   EnableTool(IDT_EDIT_COPY, !b1 && !ro);
   EnableTool(IDT_EDIT_CLEAR, !b1 && !ro);
 
-  EnableTool(IDT_VIEW_TOGGLEFOLDS, b2 && (g_bCodeFoldingAvailable && g_bShowCodeFolding) && !tv);
+  EnableTool(IDT_VIEW_TOGGLEFOLDS, b2 && (g_bCodeFoldingAvailable && g_bShowCodeFolding));
 
   EnableTool(IDT_VIEW_TOGGLE_VIEW, b2 && ((g_iMarkOccurrences > 0) && !g_bMarkOccurrencesMatchVisible));
   CheckTool(IDT_VIEW_TOGGLE_VIEW, tv);
diff --git a/src/Notepad3.rc b/src/Notepad3.rc
index 2c2700cd2..e96a5ef9f 100644
--- a/src/Notepad3.rc
+++ b/src/Notepad3.rc
@@ -332,7 +332,7 @@ BEGIN
         MENUITEM "Selection &Margin\tCtrl+Shift+M", IDM_VIEW_MARGIN
         MENUITEM SEPARATOR
         MENUITEM "Code &Folding\tCtrl+Shift+Alt+F", IDM_VIEW_FOLDING
-        MENUITEM "&Toggle All Folds\tCtrl+Shift+F", IDM_VIEW_TOGGLEFOLDS
+        MENUITEM "&Toggle Folds\tCtrl+Shift+F",     IDM_VIEW_TOGGLEFOLDS
         MENUITEM SEPARATOR
         MENUITEM "Show Tool&bar",               IDM_VIEW_TOOLBAR
         MENUITEM "C&ustomize Toolbar...",       IDM_VIEW_CUSTOMIZETB
@@ -1522,7 +1522,7 @@ BEGIN
     IDT_FILE_PRINT          "Print"
     IDT_FILE_OPENFAV        "Favorites"
     IDT_FILE_ADDTOFAV       "Add to Favorites"
-    IDT_VIEW_TOGGLEFOLDS    "Toggle All Folds"
+    IDT_VIEW_TOGGLEFOLDS    "Toggle Folds"
     IDT_FILE_LAUNCH         "Execute Document"
     IDT_VIEW_TOGGLE_VIEW    "Focused View"
 END
diff --git a/src/SciCall.h b/src/SciCall.h
index 399b52840..e1667baf0 100644
--- a/src/SciCall.h
+++ b/src/SciCall.h
@@ -309,12 +309,13 @@ DeclareSciCallV2(IndicatorFillRange, INDICATORFILLRANGE, DocPos, position, DocPo
 //
 //
 DeclareSciCallR1(GetLineVisible, GETLINEVISIBLE, bool, DocLn, line)
-DeclareSciCallV2(SetFoldLevel, SETFOLDLEVEL, DocLn, line, int, flags)
+DeclareSciCallV2(SetFoldLevel, SETFOLDLEVEL, DocLn, line, int, level)
 DeclareSciCallR1(GetFoldLevel, GETFOLDLEVEL, int, DocLn, line)
 DeclareSciCallV1(SetFoldFlags, SETFOLDFLAGS, int, flags)
 DeclareSciCallV1(FoldDisplayTextSetStyle, FOLDDISPLAYTEXTSETSTYLE, int, flags)
-DeclareSciCallR1(GetFoldParent, GETFOLDPARENT, int, DocLn, line)
-DeclareSciCallR1(GetFoldExpanded, GETFOLDEXPANDED, int, DocLn, line)
+DeclareSciCallR1(GetFoldParent, GETFOLDPARENT, DocLn, DocLn, line)
+DeclareSciCallR2(GetLastChild, GETLASTCHILD, DocLn, DocLn, line, int, level)
+DeclareSciCallR1(GetFoldExpanded, GETFOLDEXPANDED, bool, DocLn, line)
 DeclareSciCallV1(ToggleFold, TOGGLEFOLD, DocLn, line)
 DeclareSciCallV1(FoldAll, FOLDALL, int, flags)
 DeclareSciCallV1(EnsureVisible, ENSUREVISIBLE, DocLn, line)