When I turn on preference showDebugDamage there are some issues when dropping tiles in the ScriptEditor. A rectangle in the top left corner flashes, and a large part of the screen is redrawn when the tile is dropped, from top left of screen to bottom right of ScriptEditor. I guess this will slow the tile scripting responsiveness. Also the Viewer flap tabs are redrawn quite often, not flap tabs for SketchMorphs, but for other morphs. Karl