I hope I can explain this clearly enough. I have my main form (A) and it opens 1 child form (B) using form.Show() and a second child form (C) using form.Show(). Now I want child form B to open a form (D) using form.ShowDialog(). When I do this, it blocks form A and form C as well. Is there a way to open a modal dialog and only have it block the form that opened it?
If you run Form B on a separate thread from A and C, the ShowDialog call will only block that thread. Clearly, that's not a trivial investment of work of course.
You can have the dialog not block any threads at all by simply running Form D's ShowDialog call on a separate thread. This requires the same kind of work, but much less of it, as you'll only have one form running off of your app's main thread.