Question

vwait forever runs the events loop until the exit command.

I have some stuff to do during each iteration of the event loop. How can I do that?

Answer 1

You don’t. What you do is schedule regular timer events that do your work. For user interaction, 10 times a second is quite regular enough. To schedule regular timer events, use the every command from the Tcler’s Wiki, like this:

proc every {ms body} {after $ms [info level 0]; eval $body}
every 100 {
    puts "I'm saying Hi ten times a second!"
}

That’s the simplest form of every; more complex cancelable versions are further down that wiki page.