It would be great if you could restrict Undo to the activ model.
Currently, pressing Ctrl+Z would undo the placement of element you did in the previous model.
Workflow:
A design with several models.
Place some elements in model A
Change to model B
Place some elements
Press Ctrl+Z to undo the the placement of elements in model B.
If you press Ctrl+Z once to many it will undo the elements in model A.
Regards,
Krister Surell