Problems with Modal GP AddIn Window

I recently developed a GP AddIn that provided an extra options window for the Vendor Maintenance GP window. For a given vendor ID, the window allowed the user to store a list of attributes for the vendor.

It worked fine and was pretty straightforward--until I tried to make it a modal window.

When I used .ShowDialog, the window would display, but it would not respond to mouse events (brief video - IE and Flash required).

Clicking on check boxes did nothing, Save and Cancel would not work, I could not move or reposition the window, and even the control box buttons in the upper right corner of the window would not respond to a mouse click. But I could still use the keyboard to tab through the window controls, and could press the ESC key to close the window.

After further testing, it turned out that the modal window worked properly the first time it was displayed. After that, the problem occurred and would not go away until GP was shut down and restarted.

After posting to Steve Gray's excellent Dynamics GP development forum on Visual Studio tools (and seeing that someone else had the exact same issue), he assured me that he uses Modal AddIn windows all of the time, and that it definitely should work. So I tried creating a new GP window form from scratch in my VS project, but had the same issue. The next test that Steve recommended was to create a new project from scratch with just a plain modal window and no additional code.

Unfortunately, before I could try that test, my virtual server bit the dust, and my last full backup of the VHD was from August (ya, I know, I know, lesson learned). So after restoring my August backup, I saw that I didn't even have the VS Tools SDK installed. So I installed it, along with SDK 10 SP3, and tried to create a new test project.

Well, the problem no longer existed--now my modal AddIn windows work fine. So unfortunately I don't have a specific resolution other than to let you know that you aren't going crazy if you run into this issue, and just to recommend installing the latest Visual Studio Tools SDK service pack and see if that does the trick. If it does not, then it would seem to be something related to the development machine that is causing the issue.