It would be nice if undo/redo functionality could be temporarily suppressed for a given set of operations, and later restored. Any framework that supports undo/redo should allow for this, regardless of whether an UndoManager is available.

UndoManager available && !suppressed -> do undo/redo
UndoManager !available && !suppressed -> no undo/redo
UndoManager available && suppressed -> no undo/redo
UndoManager !available && suppressed -> no undo/redo

The implementation should be based on a counter rather than a flag, so it
allows for nested, balanced calls to suppressUndo() and restoreUndo().

The Quantum Engine API provides this functionality through the interfaces
appended below, but I'm afraid it has not been tested much.