Multiple undo and redo

[Malte Brill]

 > Malte, what did you do for drops, where you have 5 undos?

I did something I would not do again. :-)
I am cloning the playgrid and copy it to an undo card. If there are  
more than 5 groups on that card I delete the one with the lowest  
layer. when undoing I copy the one with the highest layer back to the  
main card and delete it on the undo card. However, a much nicer  
approach will be to store states in a custom property set and go from  
there.

like undo[1],undo[2],...undo[n|

and store all relevant data there.

All the best,

Malte