as soon as the first click is received set a flag m.inProcess = true or something.  In your init sub, set m.inProcess = false.  In your onKeyEvent check if m.inProcess then return true so the click is ignored.  When your thing finishes adding or later goes away you need to set m.inProcess back to false so you start listening for clicks on that screen / component again.

what is your keypress code? the firmware fires both "press" and "release" events for a single button click. for example:

' press is true for the down phase, false for the release phase . 
function onKeyEvent(key, press) as Boolean
if press
 ...do stuff...
end if