Invalid premise in detectFullscreen

[a-stewart]

If you run insiders.vscode.dev on a PWA in Linux with multiple monitors and WCO enabled, the window controls are on top of the icons on the right.

The issue is that there is a bad premise in dom.ts.

	if (targetWindow.innerHeight === targetWindow.screen.height) {
		// if the height of the window matches the screen height, we can
		// safely assume that the browser is fullscreen because no browser
		// chrome is taking height away (e.g. like toolbars).
		return { mode: DetectedFullscreenMode.BROWSER, guess: false };
	}

The problem with this is that if you are on a Linux machine with a secondary screen (so no task bar), with the App running as a PWA and with window controls overlay enabled, then the regular - non full screen but maximised window will be the same height as the screen height.

As such it will falsely report being fullscreen and the window controls will render on top of the icons, since the css includes:

.monaco-workbench.fullscreen .part.titlebar .window-controls-container {
    display: none;
    background-color: transparent;
}

There is a secondary issue that window.screen seems to be faulty on Chrome/Linux too which means sometimes it gets the wrong screen, and that results in the PWA actually rendering correctly which makes this tricky to debug.

[a-stewart]

This also causes a second issue when you have `Window: Menu Bar Visibility" which causes the menu bar to be hidden when you maximise VS Code.