title: How to write a TCL procedure that does something in an infinite loop until a user key press is detected?
body: <p>I am not sure how this is to be done in TCL. So basically, I need to write a procedure that will execute at 500ms intervals until a key is pressed. A key press will basically cause it to exit. How can this be written in TCL? I don't know how to detect key presses in TCL.</p>