Another question on the undo stack, is it possible to prevent operations from appearing in the undo stack at all? To basically have transparent actions that are never added to the stack?
In certain cases I have to show/hide entities during an input stage, and that clutters the undo stack. It's possible to move them into one operation, but the stack looks something like
Operation 1
hide/show-operations
Operation 2
Which adds an unnecessary undo step (as I undo all the operations performed in the ruby code).