fix "holding left and pressing right ignores wheel lock"

stepmania/src/ScreenSelectMusic.cpp

@@ -809,10 +809,10 @@ void ScreenSelectMusic::Input( const InputEventPlus &input )
 					switch( input.MenuI.button )
 					{
 					case MENU_BUTTON_LEFT:
-						m_MusicWheel.ChangeMusic( -1 );
+						m_MusicWheel.ChangeMusicUnlessLocked( -1 );
 						break;
 					case MENU_BUTTON_RIGHT:
-						m_MusicWheel.ChangeMusic( +1 );
+						m_MusicWheel.ChangeMusicUnlessLocked( +1 );
 						break;
 					}
 				}

stepmania/src/WheelBase.cpp

@@ -495,6 +495,22 @@ void WheelBase::TweenOffScreenUpdateItems(bool changing_sort)
 	}
 }
 
+void WheelBase::ChangeMusicUnlessLocked( int n )
+{
+	if( m_WheelState == STATE_LOCKED )
+	{
+		if(n)
+		{
+			int iSign = n/abs(n);
+			m_fLockedWheelVelocity = iSign*LOCKED_INITIAL_VELOCITY;
+			m_soundLocked.Play();
+		}
+		return;
+	}
+
+	ChangeMusic( n );
+}
+
 void WheelBase::Move(int n)
 {
 	if(n == m_Moving)

stepmania/src/WheelBase.h

@@ -33,6 +33,7 @@ public:
 	void TweenOffScreen() { TweenOffScreen(false); }
 
 	void Move(int n);
+	void ChangeMusicUnlessLocked( int n ); /* +1 or -1 */
 	virtual void ChangeMusic(int dist); /* +1 or -1 */
 
 	/* Return true if we're moving fast automatically. */