Original Article: http://weblogs.asp.net/rosh... Problem & Solution: Allow only one instance of any MDI child form in your MDI application One of the things I needed to do at an MDI application I was involved with was the ability to only load a specific form once, and make sure it does not load again. That form could not be modal, but could only have one instance running inside the MDI parent. I came up with a rather elegant solution, if I do say so myself :)...