I just submitted the above feedback report. I was migrating a 32-bit app I had developed in Xojo R2015 and was modifying the code I was using for preferences and eliminating MacOSLib code. I kept getting crashes and believed that the code that I was adding was the culprit. After debugging for a while I could not find a cause and started to comment out code to narrow down the problem. I kept going until there was no event code for the preference window that I was building and just opening and closing the window multiple times could crash the app. I then suspected that the window might be corrupt somehow and I build it from scratch with the same results. I then culled app code until all that is left is the app menu item to open the dialog window. I then culled the dialog window controls until only two popupmenus remain. It will crash when run 32-bit, I could not get a crash on 64-bit. I can’t seem to make it crash on 2015 thru 2018 versions of Xojo. The number of times that the window has to be opened and closed to create a crash is random and can take from 1 to about 15 times. Hopefully Xojo can reproduce from the code that I submitted.