make system context menu code more understandable

[sbatten]

refs #155276

I've added comments and checks for when the mouse is not within the bounds of the title bar

[bpasero]

I cannot really review without understanding what exactly this code does. At the very very minimum, explain it in JSDoc comments.

[bpasero]

Looks like its coming from https://docs.microsoft.com/en-us/windows/win32/menurc/wm-initmenu?redirectedfrom=MSDN. Is this the officially accepted solution from Electron?

[bpasero]

Should we at least check if the context menu is triggered over the bounds of the title area?

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

Lines 204 to 211 in 09259ab

	this._register(this.nativeHostService.onDidTriggerSystemContextMenu(({ windowId, x, y }) => {
	if (this.nativeHostService.windowId !== windowId) {
	return;
	}
	const zoomFactor = getZoomFactor();
	this.onContextMenu(new MouseEvent('mouseup', { clientX: x / zoomFactor, clientY: y / zoomFactor }), MenuId.TitleBarContext);
	}));