Hi Tim.
It's not really abou knowing C#, its more about AutoCAD
and MDI, which is something you generally don't have to
contend with when using LISP.
I think you might want to test how your code works when
you switch to a document that has a command already
running in it. E.g., start the LINE command or some other
AutoCAD command, then while it's waiting for input, switch
to another document, then switch back to the one that
has the running command.
Tony, thanks again for your input, I find it invaluable.
Some of what you say makes sense to me, but some has me scratching my head. I knew I didn't know much about C#, but know I'm finding I know a whole lot less than I thought I did. I will do some research and see if I can solve this problem, and maybe in doing so I will be able to see if there are any other problems.