private boolean contains( Rectangle rect, Point pt ) {
			return (rect != null && rect.contains( pt ) );
		}
Handle WM_NCHITTEST

https://docs.microsoft.com/en-us/windows/win32/inputdev/wm-nchittest

See also NonClientIslandWindow::_OnNcHitTest() here:
https://github.com/microsoft/terminal/blob/main/src/cascadia/WindowsTerminal/NonClientIslandWindow.cpp
flatlaf-natives/flatlaf-natives-jna/src/main/java/com/formdev/flatlaf/natives/jna/windows/FlatWindowsNativeWindowBorder.java