Exiting my skill code when a new command is started

How do I detect and gracefully exit my skill code when a new Allegro command like "slide" is started?  If another command is started while I'm waiting for a selection, the new command is put on hold until Cancel or Done is selected in my popup; then the new command starts.  I would rather have my code do a "Done" when the new command is selected so the new command starts right away (similar to how you can go from one Allegro command to another with selecting Done; i.e. Slide to Add Connect.

;setup popup with Cancel/Done items

while( axlSelect()

;    user selects database items and they are modified based on input form settings

);end while