DragListener should only stop dragging when touchUp matches the butto…

…n it cares about. (#7389)

gdx/src/com/badlogic/gdx/scenes/scene2d/utils/DragListener.java

@@ -63,7 +63,7 @@ public void touchDragged (InputEvent event, float x, float y, int pointer) {
 	}
 
 	public void touchUp (InputEvent event, float x, float y, int pointer, int button) {
-		if (pointer == pressedPointer) {
+		if (pointer == pressedPointer && (this.button == -1 || button == this.button)) {
 			if (dragging) dragStop(event, x, y, pointer);
 			cancel();
 		}