private static Window getDefaultParentWindow() {
		KeyboardFocusManager kfm = KeyboardFocusManager.getCurrentKeyboardFocusManager();
		Window activeWindow = kfm.getActiveWindow();
		if (activeWindow == null) {
			activeWindow = JOptionPane.getRootFrame();
		}
		return activeWindow;
	}
Area where user can mouse without hiding the window (in screen coordinates).  A.K.A., the
mouse neutral zone.
Ghidra/Framework/Docking/src/main/java/docking/widgets/PopupWindow.java