How to support undo of VB actions

I have a VB dll which adds items to the drawing. How do I group all the actions into a single or multiple undos. After the DLL exits I would like the user to have the option of undoing what was done.

At the moment I have done nothing in this regard and the undo does work just not very well. On my last test the first undo often did nothing and the second worked but then a third undo associated with the dll actually undid stuff that the user did prior to running the dll.

 

ThisDrawing.StartUndoMark
ThisDrawing.EndUndoMark
hth
Mark

actions into a single or multiple undos. After the DLL exits I would like
the user to have the option of undoing what was done.

just not very well. On my last test the first undo often did nothing and the
second worked but then a third undo associated with the dll actually undid
stuff that the user did prior to running the dll.

 

Thanks, will try...

What I'm getting now for my Path Tracker command which opens a VB DLL dialog window is the following sequence:

run custom dll dialog and exit
undo #1 = UNDO - OLEAPPLICATION (does nothing)
undo #2 = UNDO - Path Tracker (works)