How to handle "On" key - & - Safe file storage

[Jacob Wall]

It appears the HP Prime's "On" key always interrupts a program and there's no way to handle this situation with WAIT(-1), or other methods that I've tried. I can see potentially why this might be a good thing, but for me the "On" key was always the same as "Cancel" (50g), while there's an "Esc" key on the Prime. Question, is it a matter of re-training myself not to use "On" for the purpose of "Cancel"/"Esc" or is there a way someone has found to handle this key press?

This started giving me grief because I was using a method to save a list of variable values to AFiles on EXIT of an app, then restoring on start-up, but the synchronize is broken if the program is interrupted. The reason I saved to AFiles in the first place was because an "update" to the app's program clears the variables (global variables) and I need a reliable way to save data associated with an app, regardless if the app is updated over time. For that matter, a method to save files to a safe area would be fantastic. Maybe HVars is intended for this? App variables do make a lot of sense, however unreliable as they are very vulnerable to total loss when an app is "updated".

AFilesB is handy, is there a HVars equivalent?