BTW, did you set some kind of "Custom Scale Factor" or "DPI" on your machine? The buttons look "old-style" and "larger" than normal. I checked our support records and as far as I can see, we have not received a similar support request in all the years (and there are quite a few thousand SetupBuilder developers out there). My screenshot is from a 1920 x 1080 resolution machine. I have tested your script on XP, Windows 7, Windows 8.1, Windows 10 and Server 2016. The custom dialog displayed as expected here.

Friedrich