private void updateWindowBackground() {
			Color bg = window.getBackground();
			if( bg != null )
				setWindowBackground( hwnd, bg.getRed(), bg.getGreen(), bg.getBlue() );
		}
Because there may be sent many WM_DWMCOLORIZATIONCOLORCHANGED messages,
slightly delay event firing and fire it only once (on the AWT thread).
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatWindowsNativeWindowBorder.java