don't reload note skin when entering play mode in the editor

stepmania/src/NoteField.cpp

@@ -51,6 +51,8 @@ void NoteField::Unload()
 
 void NoteField::CacheNoteSkin( CString skin )
 {
+	skin.ToLower();
+
 	if( m_NoteDisplays.find(skin) != m_NoteDisplays.end() )
 		return;
 
@@ -64,13 +66,38 @@ void NoteField::CacheNoteSkin( CString skin )
 	m_NoteDisplays[ skin ] = nd;
 }
 
-void NoteField::CacheAllUsedNoteSkins()
+void NoteField::CacheAllUsedNoteSkins( bool bDeleteUnused )
 {
 	/* Cache note skins. */
 	vector<CString> skins;
 	GAMESTATE->GetAllUsedNoteSkins( skins );
 	for( unsigned i=0; i < skins.size(); ++i )
 		CacheNoteSkin( skins[i] );
+
+	if( bDeleteUnused )
+	{
+		set<CString> setToDelete;
+		for( map<CString, NoteDisplayCols *>::iterator it = m_NoteDisplays.begin();
+			it != m_NoteDisplays.end(); ++it )
+		{
+			setToDelete.insert( it->first );
+		}
+
+		for( unsigned i=0; i < skins.size(); ++i )
+		{
+			CString sSkin = skins[i];
+			sSkin.ToLower();
+			setToDelete.erase( sSkin );
+		}
+
+		/* Free note skins that are no longer used. */
+		for( set<CString>::iterator it = setToDelete.begin(); it != setToDelete.end(); ++it )
+		{
+			NoteDisplayCols *pNoteDisplay = m_NoteDisplays[*it];
+			delete pNoteDisplay;
+			m_NoteDisplays.erase( *it );
+		}
+	}
 }
 
 void NoteField::Load( 
@@ -98,7 +125,9 @@ void NoteField::Load(
 	this->CopyAll( *pNoteData );
 	ASSERT( GetNumTracks() == GAMESTATE->GetCurrentStyle()->m_iColsPerPlayer );
 
-	CacheAllUsedNoteSkins();
+	/* If we're in gameplay, we havn't applied course modifiers yet, so we don't know what
+	 * note skins we'll need. Don't delete unused skins yet. */
+	CacheAllUsedNoteSkins( false );
 	RefreshBeatToNoteSkin();
 }