Reason for using Interrupt:
on pressing START button loop() will call another declared function RunAuto() / RunSemiAuto() / RunManual(). It will stay in the loop until function is completed. I need an interrupt on stop switch to get out of that loop and move to another page of LCD in display "PAUSED". I can't scan for pushbuttons as above function will stay in while loop.
About Hardware Problem: I'm avoiding to strip off entire control panel just to add extra switch. And if it can be avoided with cleaver piece of code that'll be great!