Load Background's BGAs on first load, not in the ctor, so Jukebox and

Demonstration set up first; otherwise, BGAs with Lua expressions that
depend on them won't work.

stepmania/src/Background.cpp

@@ -40,6 +40,15 @@ Background::Background()
 	m_pCurrentBGA = NULL;
 	m_pFadingBGA = NULL;
 	m_fSecsLeftInFade = 0;
+	m_pDancingCharacters = NULL;
+	m_bInitted = false;
+}
+
+void Background::Init()
+{
+	if( m_bInitted )
+		return;
+	m_bInitted = true;
 
 	m_DangerAll.LoadFromAniDir( THEME->GetPathToB("ScreenGameplay danger all") );
 	FOREACH_PlayerNumber( p )
@@ -63,8 +72,6 @@ Background::Background()
 
 	if( bOneOrMoreChars && !bShowingBeginnerHelper )
 		m_pDancingCharacters = new DancingCharacters;
-	else
-		m_pDancingCharacters = NULL;
 
 	m_quadBorder[0].StretchTo( RectF(SCREEN_LEFT,SCREEN_TOP,LEFT_EDGE,SCREEN_BOTTOM) );
 	m_quadBorder[0].SetDiffuse( RageColor(0,0,0,1) );
@@ -284,6 +291,8 @@ void Background::LoadFromRandom( float fFirstBeat, float fLastBeat, const Timing
 
 void Background::LoadFromSong( const Song* pSong )
 {
+	Init();
+
 	Unload();
 
 	m_pSong = pSong;

stepmania/src/Background.h

@@ -33,6 +33,7 @@ class Background : public ActorFrame
 public:
 	Background();
 	~Background();
+	void Init();
 
 	virtual void LoadFromSong( const Song *pSong );
 	virtual void Unload();
@@ -55,6 +56,7 @@ protected:
 	bool IsDeadPlayerVisible( PlayerNumber pn );
 	void UpdateCurBGChange( float fCurrentTime );
 	
+	bool m_bInitted;
 	DancingCharacters*	m_pDancingCharacters;
 
 	BGAnimation		m_DangerPlayer[NUM_PLAYERS];