Version: Revision 1042832 (using KDE 4.3.2)
Installed from: Ubuntu Packages
Take a look at the video.
Basically, whenever I use any of the paint tools and then undo, it seems to delete all the tiles that were drawn on. Drawing tools do not have this problem, and strangely, if I rotate the canvas the problem goes away.
Created attachment 37982 [details]
Ogg video showing undo of paint tools before and after canvas rotate
This is the same problem as 212235. Dmitry was going to look at it this weekend :-)
*** This bug has been marked as a duplicate of bug 212235 ***