My sketch disappears!

Since upgrading to 1.6.3 my IDE and sketch with all its edits just disappears suddenly. I have XP sp3. Anyone else have this problem? It seems that it happens when I have more than one sketch displayed.

I find it annoying that the IDE has no provision for bringing a specific sketch forward. If a sketch falls behind another sketch window it becomes unreachable until the windows in front of it are moved or closed. Could that be the problem you are having?