I just wasted an entire weekend with a problem I am sure is related to the issue in this article. I was creating a custom item additional information window using C#. I was just wrapping up a lookup window and went to test. As soon as I went to select the item GP would crash. I was using code I have used hundreds of times before and after meticulous debugging it came down to something to do with either Close() or Dispose(). It all revolves around something to do with DEXUIForm. I switch back to just Form and all is well, although I lose the GP colors and lines.
https://dynamicsgpland.blogspot.com/2015/01/bug-in-dynamics-gp-vs-tools-event.html
I am hoping this fall to take Dave up on his Dexterity training but for now I am curious as to what it is about DEXUIForm that made my lookup window crash.