In the following example I'm trying to get a scale to run a command without
slowing down the slider motion. I'm using update within the command's loop,
and using a global variable to prevent more than one instance of the command
from running at a time, but the slider still freezes up. Does anyone know
why, and how I can get around it? BTW I'm using tcl8.2 and I've tried in on
Windows98 and HPUX.

thanks in advance.

# create and pack scale
scale .s -command {command1}
pack .s -fill y

#diagnostic output file
set output [open output.txt w]

set working N

proc command1 {args} {
  global working j output
  if {$working} {
    # already working, so don't do anything
    puts $output "already working"
  } else {
    set working Y
    # do something in a loop
    for {set j 0} {$j < 1000} {incr j} {
      puts $output "working, $j"
      update
    }
    set working N
  }