Is there any way to change the number of choices in the Duration dropdown box on the event edit screen?
Yes. You may edit the file called eventedit.dat in the same folder as the calendar in question. There is a section called [DURATIONS] which is mostly self explanatory. Each item in the list (except the first which details the number of remaining items in the list) consists of three parts: dirN=prompt|value in minutes Add as many or as few items as you like following this format. Make sure to adjust the nDurs item to reflect to correct number of items in the list.