AddCustomUndoEvent

import Rhino
import scriptcontext


def OnUndoFavoriteNumber(sender, e):
    """!!!!!!!!!!
    NEVER change any setting in the Rhino document or application.  Rhino
    handles ALL changes to the application and document and you will break
    the Undo/Redo commands if you make any changes to the application or
    document. This is meant only for your own private plug-in data
    !!!!!!!!!!

    This function can be called either by undo or redo
    In order to get redo to work, add another custom undo event with the
    current value.  If you don't want redo to work, just skip adding
    a custom undo event here
    """
    current_value = scriptcontext.sticky["FavoriteNumber"]
    e.Document.AddCustomUndoEvent("Favorite Number", OnUndoFavoriteNumber, current_value)

    old_value = e.Tag
    print "Going back to your favorite =", old_value
    scriptcontext.sticky["FavoriteNumber"]= old_value;


def TestCustomUndo():
    """Rhino automatically sets up an undo record when a command is run,
       but... the undo record is not saved if nothing changes in the
       document (objects added/deleted, layers changed,...)
    
       If we have a command that doesn't change things in the document,
       but we want to have our own custom undo called then we need to do
       a little extra work
    """
    current_value = 0
    if scriptcontext.sticky.has_key("FavoriteNumber"):
        current_value = scriptcontext.sticky["FavoriteNumber"]
    rc, new_value = Rhino.Input.RhinoGet.GetNumber("Favorite number", True, current_value)
    if rc!=Rhino.Commands.Result.Success: return

    scriptcontext.doc.AddCustomUndoEvent("Favorite Number", OnUndoFavoriteNumber, current_value);
    scriptcontext.sticky["FavoriteNumber"] = new_value

if __name__=="__main__":
    TestCustomUndo()

Imports System.Runtime.InteropServices
Imports Rhino

<Guid("A6924FE1-2B94-4918-94F3-B8935B8DC80C")> _
Public Class ex_customundoCommand
  Inherits Rhino.Commands.Command
  Public Overrides ReadOnly Property EnglishName() As String
    Get
      Return "vb_CustomUndoCommand"
    End Get
  End Property

  Private Property MyFavoriteNumber() As Double
    Get
      Return m_MyFavoriteNumber
    End Get
    Set(value As Double)
      m_MyFavoriteNumber = value
    End Set
  End Property
  Private m_MyFavoriteNumber As Double

  Protected Overrides Function RunCommand(doc As RhinoDoc, mode As Rhino.Commands.RunMode) As Rhino.Commands.Result
    ' Rhino automatically sets up an undo record when a command is run,
    ' but... the undo record is not saved if nothing changes in the
    ' document (objects added/deleted, layers changed,...)
    '
    ' If we have a command that doesn't change things in the document,
    ' but we want to have our own custom undo called then we need to do
    ' a little extra work

    Dim d As Double = MyFavoriteNumber
    If Rhino.Input.RhinoGet.GetNumber("Favorite number", True, d) = Rhino.Commands.Result.Success Then
      Dim current_value As Double = MyFavoriteNumber
      doc.AddCustomUndoEvent("Favorite Number", AddressOf OnUndoFavoriteNumber, current_value)
      MyFavoriteNumber = d
    End If
    Return Rhino.Commands.Result.Success
  End Function

  ' event handler for custom undo
  Private Sub OnUndoFavoriteNumber(sender As Object, e As Rhino.Commands.CustomUndoEventArgs)
    ' !!!!!!!!!!
    ' NEVER change any setting in the Rhino document or application.  Rhino
    ' handles ALL changes to the application and document and you will break
    ' the Undo/Redo commands if you make any changes to the application or
    ' document. This is meant only for your own private plug-in data
    ' !!!!!!!!!!

    ' This function can be called either by undo or redo
    ' In order to get redo to work, add another custom undo event with the
    ' current value.  If you don't want redo to work, just skip adding
    ' a custom undo event here
    Dim current_value As Double = MyFavoriteNumber
    e.Document.AddCustomUndoEvent("Favorite Number", AddressOf OnUndoFavoriteNumber, current_value)

    Dim old_value As Double = CDbl(e.Tag)
    RhinoApp.WriteLine("Going back to your favorite = {0}", old_value)
    MyFavoriteNumber = old_value
  End Sub
End Class