Adds an undo history entry.
Adds an undo history entry. Properly cuts the redo history before adding and merges if supported.
the history entry to add
if set to true the redo method will be invoked on the entry before it is added (defaults to false)
Clears all undo and redo history.
Cuts off all the redo history.
Cuts off all the redo history. Called before adding to the history.
Returns true if the history state is currently being modified (undoing or redoing).
Returns the next step forward in history (into the redos) or None if there are no history entries to go forward to.
Returns the next step forward in history (into the redos) or None if there are no history entries to go forward to.
Does not modify the history state.
Returns the next step backward in history (into the undos) or None if there are no history entries to go back to.
Returns the next step backward in history (into the undos) or None if there are no history entries to go back to.
Does not modify the history state.
Goes forward one step in history if there is redo history available.
Goes forward one step in history if there is redo history available.
true if history moved forward one step, false if there is no redo history
Goes backward one step in history if there is undo history available.
Goes backward one step in history if there is undo history available.
true if history moved backward one step, false if there is no undo history
Invokes the supplied function without recording any history during its invocation.
Invokes the supplied function without recording any history during its invocation. This is primarily for undo and redo manipulation internally.