>Yes I did get both AddToMenu and RemoveFromMenu to work. However, I'm now working with Set Mark of... I'd like the active form instance to be marked but can't get this to work properly. I'm trying to set the menu's mark from the form's activate() but this results in 'no such menu or menu item is defined' even though the item is definitely on the menu. Any ideas?

When ever I've used Set mark its always been with the Bar option, have you tried getting the menu bar number and using that?