How to modify this loop?

[ThunderBird]

Please look at my simple code.
Now I can input two data and click 'run', then 'stop' to stop the program.
But what I want is:
1. I can stop the program at anytime (now I can only stop the program after click 'run')
2. Before I click 'stop', I can 'run' the program any times. (right now it can only be run once).
How to change this loop? Thanks.

- TBird

[chilly_charly]

Is that what you want ?
CC

[ThunderBird]

It works good, thank you