Added spacer widget to handle mouse events properly in CDockAreaTitle…

…Bar, added missing updateGeometry calls to CDockAreaTabBar

src/DockAreaTabBar.cpp

@@ -445,9 +445,15 @@ bool CDockAreaTabBar::eventFilter(QObject *watched, QEvent *event)
 	switch (event->type())
 	{
 	case QEvent::Hide:
-		 emit tabClosed(d->TabsLayout->indexOf(Tab)); break;
+		 emit tabClosed(d->TabsLayout->indexOf(Tab));
+		 updateGeometry();
+		 break;
+
 	case QEvent::Show:
-		 emit tabOpened(d->TabsLayout->indexOf(Tab)); break;
+		 emit tabOpened(d->TabsLayout->indexOf(Tab));
+		 updateGeometry();
+		 break;
+
 	default:
 		break;
 	}

src/DockAreaTitleBar.cpp

@@ -185,6 +185,30 @@ class CTitleBarButton : public tTitleBarButton
 };
 
 
+/**
+ * This spacer widget is here because of the following problem.
+ * The dock area title bar handles mouse dragging and moving the floating widget.
+ * The  problem is, that if the title bar becomes invisible, i.e. if the dock
+ * area contains only one single dock widget and the dock area is moved
+ * into a floating widget, then mouse events are not handled anymore and dragging
+ * of the floating widget stops.
+ */
+class CSpacerWidget : public QWidget
+{
+	Q_OBJECT
+public:
+	using Super = QWidget;
+	CSpacerWidget(QWidget* Parent = 0)
+	    : Super(Parent)
+	{
+	    setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
+	    setStyleSheet("border: none; background: none;");
+	}
+	virtual QSize sizeHint() const override {return QSize(0, 0);}
+	virtual QSize minimumSizeHint() const override {return QSize(0, 0);}
+};
+
+
 //============================================================================
 DockAreaTitleBarPrivate::DockAreaTitleBarPrivate(CDockAreaTitleBar* _public) :
 	_this(_public)
@@ -322,8 +346,7 @@ CDockAreaTitleBar::CDockAreaTitleBar(CDockAreaWidget* parent) :
 	setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Fixed);
 
 	d->createTabBar();
-	auto horizontalSpacer = new QSpacerItem(0, 0, QSizePolicy::Expanding, QSizePolicy::Minimum);
-	d->Layout->addSpacerItem(horizontalSpacer);
+	d->Layout->addWidget(new CSpacerWidget(this));
 	d->createButtons();
 }