It's drawn twice, once for each buffer, seeing as you're flipping for the glowing players you need to same image on each buffer or it goes flicka-flicka-flicka-flika...
DOH! I hardly ever run fullscreen and in windowed you don't get that flicker.With regards to the vis, the above function replacement for damageTile should work. It adds a "checkVis(x,y)" call after you've blown the door so even if the door has a single tile missing the new vis gets updated. As for the other parts of the door getting blown up, it's because the default action for killing a door *without* a script attached is just to kill that tile and not any surrounding tiles. I'm not sure where the piece of code that accomplished this before has gone.