@SuppressWarnings( "rawtypes" )
		@Override
		public int selectionForKey( char aKey, ComboBoxModel aModel ) {
			long time = EventQueue.getMostRecentEventTime();
			long oldLastTime = lastTime;
			lastTime = time;

			// SPACE key shows popup if not yet visible
			if( aKey == ' ' &&
				time - oldLastTime >= timeFactor &&
				!comboBox.isPopupVisible() )
			{
				comboBox.setPopupVisible( true );
				return -1;
			}

			return delegate.selectionForKey( aKey, aModel );
		}
Key selection manager that delegates to the default manager.
Shows the popup if Space key is pressed and "typed characters" buffer is empty.
If items contain spaces (e.g. "a b") it is still possible to select them
by pressing keys 'a', 'Space' and 'b'.
flatlaf-core/src/main/java/com/formdev/flatlaf/ui/FlatComboBoxUI.java