static synchronized boolean install() {
		if( instance != null )
			return false;

		if( !FlatSystemProperties.getBoolean( FlatSystemProperties.USE_SUB_MENU_SAFE_TRIANGLE, true ) )
			return false;

		instance = new SubMenuUsabilityHelper();
		MenuSelectionManager.defaultManager().addChangeListener( instance );
		return true;
	}
Improves usability of submenus by using a
<a href="https://height.app/blog/guide-to-build-context-menus#safe-triangle">safe triangle</a>
to avoid that the submenu closes while the user moves the mouse to it.

@author Karl Tauber
flatlaf-core/src/main/java/com/formdev/flatlaf/SubMenuUsabilityHelper.java