Thanks for your reply!
Unfortunately, this doesn't work either. I've tried both Alt and Ctrl on the 8 button, but it doesn't do anything. Also, on my Azerty-keyboard, the \ button is the third option under the < button, like your qwerty. But that doesn't work either, nor with Altr or Ctrl.
As for the re-editting of the shorcut-keys, yes I can, but the 'rotate building' option isn't in the list of shortcut-keys?!
Kind of a cr*ppy situation ;')