Stop when ESC is pressed

[sunchase]

Hi!

I made a little programme, that demonstrates Monte Carlo method. In this I would like to use a while loop, so it draws points until user presses ESC or ENTER.
How can I do this? What I've tried so far just made an error when ESC was pressed.

Thx for your help!

[scot-65]

(while (> (getvar "cmdactive") 0) (command pause) );while

???