Adds an undo step to the undo stack.

Returns true, if there is a step on the redo stack

Returns true, if there is a step on the undo stack

After several changes "using contextFrame" you can reset the context so that the following changes with the same context generate a new undo step.

Closes the previously opened undo frame. See OpenUndoFrame()()()().

All calls to AddUndoStep(ReversibleChange) that appeare inside the same context are considered to belong to the same action and override the previous call from the same context. So only the last call will be saved in the undo stack. Use ContextFrame with the C# "using" schema or call IDisposable.Dispose() to close the frame.

The top undostep on the undo stack will be ignored.

Opens an undo frame: all subsequent calls to AddUndoStep(ReversibleChange) are considered as a single undo step until CloseUndoFrame(Object) is beeing called. You can use the property UndoFrame instead. UndoFrames may be nested.

Executes the redo of the last step. Ususlly called by the project when handling the "MenuId.Edit.Redo" command.

Executes the undo of the last step. Ususlly called by the project when handling the "MenuId.Edit.Undo" command.