clean up RageDisplay methods, add ability to mask song banner

The masking uses the Z-buffer under the assumption that some cards don't have a stencil.  Should we be using the stencil instead?  It doesn't really matter because we never need both the Z buffer and stencil buffer simultaneously.

stepmania/src/ActorFrame.cpp

@@ -48,6 +48,10 @@ void ActorFrame::MoveToHead( Actor* pActor )
 
 void ActorFrame::DrawPrimitives()
 {
+	// Don't set Actor-defined render states because we won't be drawing 
+	// any geometry that belongs to this object.
+	// Actor::DrawPrimitives();
+
 	// draw all sub-ActorFrames while we're in the ActorFrame's local coordinate space
 	for( unsigned i=0; i<m_SubActors.size(); i++ ) {
 		m_SubActors[i]->Draw();
@@ -77,6 +81,15 @@ void ActorFrame::SetDiffuse( RageColor c )
 		m_SubActors[i]->SetDiffuse(c );
 }
 
+void ActorFrame::SetUseZBuffer( bool b )
+{
+	Actor::SetUseZBuffer( b );
+
+	// set all sub-Actors
+	for( unsigned i=0; i<m_SubActors.size(); i++ )
+		m_SubActors[i]->SetUseZBuffer( b );
+}
+
 float ActorFrame::GetTweenTimeLeft() const
 {
 	float m = Actor::GetTweenTimeLeft();