make system context menu code more understandable (#155747)

* removing unnecessary enablements
refs #155276

* add some comments

* address feedback, bring back enablements
but comment them

src/vs/platform/windows/electron-main/window.ts

@@ -292,12 +292,21 @@ export class CodeWindow extends Disposable implements ICodeWindow {
 
 			// Windows Custom System Context Menu
 			// See https://github.com/electron/electron/issues/24893
+			//
+			// The purpose of this is to allow for the context menu in the Windows Title Bar
+			//
+			// Currently, all mouse events in the title bar are captured by the OS
+			// thus we need to capture them here with a window hook specific to Windows
+			// and then forward them to the correct window.
 			if (isWindows && useCustomTitleStyle) {
+				// https://docs.microsoft.com/en-us/windows/win32/menurc/wm-initmenu
 				const WM_INITMENU = 0x0116;
+				// This sets up a listener for the window hook. This is a Windows-only API provided by electron.
 				this._win.hookWindowMessage(WM_INITMENU, () => {
 					const [x, y] = this._win.getPosition();
 					const cursorPos = screen.getCursorScreenPoint();
 
+					// This is necessary to make sure the native system context menu does not show up.
 					this._win.setEnabled(false);
 					this._win.setEnabled(true);
 

src/vs/workbench/electron-sandbox/parts/titlebar/titlebarPart.ts

@@ -207,7 +207,22 @@ export class TitlebarPart extends BrowserTitleBarPart {
 				}
 
 				const zoomFactor = getZoomFactor();
-				this.onContextMenu(new MouseEvent('mouseup', { clientX: x / zoomFactor, clientY: y / zoomFactor }), MenuId.TitleBarContext);
+				const boundingRect = this.rootContainer.getBoundingClientRect();
+				const eventPosition = { x, y };
+				const relativeCoordinates = { x, y };
+				// When comparing the coordinates with the title bar, account for zoom level if not using counter zoom.
+				if (!this.useCounterZoom) {
+					relativeCoordinates.x /= zoomFactor;
+					relativeCoordinates.y /= zoomFactor;
+				}
+
+				// Don't trigger the menu if the click is not over the title bar
+				if (relativeCoordinates.x < boundingRect.left || relativeCoordinates.x > boundingRect.right ||
+					relativeCoordinates.y < boundingRect.top || relativeCoordinates.y > boundingRect.bottom) {
+					return;
+				}
+
+				this.onContextMenu(new MouseEvent('mouseup', { clientX: eventPosition.x / zoomFactor, clientY: eventPosition.y / zoomFactor }), MenuId.TitleBarContext);
 			}));
 		}