I have modified the sample as follows:
1) Dropdowns are initially inactive; send an F12 to the grid to activate them.
2) When dropdowns are activated, only the current cell will appear as a dropdown.
3) Once dropdowns are active, play around with them a bit -- selecting cells with mouse/keyboard, and then clicking on them to bring up the dropdown. Sooner or later (but probably sooner) tracebacks will start appearing at the console.
This problem appears to happen using both 5.1 and the latest 5.2 release. Please let me know what I can do to work around it.
Cheers
William
DropDownExceptions.zip