There is a small retrograde step that has been introduced into ArchiCAD 12—probably for a good reason—but it is annoying. When you make a change on the plan, and then generate a revised perspective or elevation/section, the screen blanks out while the processing is taking place.
I much preferred it when the old version remained visible until the last moment, so you could visually search the old drawing for other problems while waiting for the computer to generate the new drawing.