Follow-up to a6ece30: allow changing volume anywhere with ALT key.

The master volume can now be changed (using the mouse wheel) with the ALT key pressed in any menu, as in osu!.

Also improved the handling of dimmed tracks.

Signed-off-by: Jeffrey Han <itdelatrisu@gmail.com>

src/itdelatrisu/opsu/states/DownloadsMenu.java

@@ -653,6 +653,12 @@ public class DownloadsMenu extends BasicGameState {
 
 	@Override
 	public void mouseWheelMoved(int newValue) {
+		// change volume
+		if (input.isKeyDown(Input.KEY_LALT) || input.isKeyDown(Input.KEY_RALT)) {
+			UI.changeVolume((newValue < 0) ? -1 : 1);
+			return;
+		}
+
 		// block input during beatmap importing
 		if (importThread != null)
 			return;