You don't need to lock or unlock. Try these do-nothing replacements. local fn LockGW( p as ptr ) end fn = _noErr local fn UnlockGW( p as ptr ) end fn = _noErr > Further...How is a 1 bit GWorld from FN NewGWorld different from a bitmap from RP's fn NewBitmap? ? IIRC, a GWorld is a PixMapHandle + various information such as bounds and colour-depth. A BitMap is a naked 1-bit PixMap.