@bobbybearing - no worries, man - and thanks.
@korruptor - had some time so checked out your source just now. Looks like it needs to be double buffered for running on 68000 - I get some flickering running it as if it's on an ECS A500+ under WinUAE - but with that amendment done it'll look great. Top man.
Only other prob I had was that it didn't quit properly for me after I pressed the left mouse button...