add chaning volume hotkey (alt+scrolling) as global hotkey

src/itdelatrisu/opsu/states/ButtonMenu.java

@@ -79,13 +79,6 @@ public class ButtonMenu extends BaseOpsuState {
 			public void leave() {
 				Button.CANCEL.click();
 			}
-
-			@Override
-			public void mouseWheelMoved(int newValue) {
-				if (displayContainer.input.isKeyDown(Input.KEY_LALT) || displayContainer.input.isKeyDown(Input.KEY_RALT)) {
-					super.mouseWheelMoved(newValue);
-				}
-			}
 		},
 		/** The initial beatmap management screen (for a "favorite" beatmap). */
 		BEATMAP_FAVORITE (new Button[] { Button.CLEAR_SCORES, Button.FAVORITE_REMOVE, Button.DELETE, Button.CANCEL }) {

src/itdelatrisu/opsu/states/DownloadsMenu.java

@@ -847,9 +847,7 @@ public class DownloadsMenu extends ComplexOpsuState {
 
 	@Override
 	public boolean mouseWheelMoved(int newValue) {
-		// change volume
-		if (displayContainer.input.isKeyDown(Input.KEY_LALT) || displayContainer.input.isKeyDown(Input.KEY_RALT)) {
-			UI.changeVolume((newValue < 0) ? -1 : 1);
+		if (super.mouseWheelMoved(newValue)) {
 			return true;
 		}
 

src/itdelatrisu/opsu/states/GameRanking.java

@@ -121,9 +121,6 @@ public class GameRanking extends BaseOpsuState {
 
 	@Override
 	public boolean mouseWheelMoved(int newValue) {
-		if (displayContainer.input.isKeyDown(Input.KEY_LALT) || displayContainer.input.isKeyDown(Input.KEY_RALT)) {
-			UI.changeVolume((newValue < 0) ? -1 : 1);
-		}
 		return true;
 	}
 

src/itdelatrisu/opsu/states/MainMenu.java

@@ -639,6 +639,10 @@ public class MainMenu extends BaseOpsuState {
 
 	@Override
 	public boolean mouseWheelMoved(int newValue) {
+		if (super.mouseWheelMoved(newValue)) {
+			return true;
+		}
+
 		UI.changeVolume((newValue < 0) ? -1 : 1);
 		return true;
 	}

src/itdelatrisu/opsu/states/SongMenu.java

@@ -1238,11 +1238,6 @@ public class SongMenu extends ComplexOpsuState {
 
 		Input input = displayContainer.input;
 
-		if (input.isKeyDown(Input.KEY_LALT) || input.isKeyDown(Input.KEY_RALT)) {
-			UI.changeVolume((newValue < 0) ? -1 : 1);
-			return true;
-		}
-
 		if (isInputBlocked()) {
 			return true;
 		}