public static void StepBack()
{
IUndoStep step = undoStack.Pop();
step.Undo();
redoStack.Push(step);
}
public static void StepForward()
{
IUndoStep step = redoStack.Pop();
step.Redo();
undoStack.Push(step);
}
public static void Push(IUndoStep step)
{
undoStack.Push(step);
redoStack = new Stack<IUndoStep>();
}
public static void Push(IUndoStep step)
{
undoStack.Push(step);
redoStack = new Stack <IUndoStep>();
}