First of all, thanks for pointing that out - you are absolutely right (no shocker there), removing that sleep fixes the double-Tab issue. Why am I using it? B/c that is what the code I borrowed had. Why did the original code have it? I believe to give it that flashing red background effect...something I can (and will) live without.

However, the issue is still there if a textvariable is pre-defined with a bad string (as I noted in the update to my OP). This is more important than the other issue, b/c this will definitely crop up. The textvariable may or may not be pre-defined before displaying the widget, but if it is, and it is invalid, I would like validation to work.

Any idea what is going on there?

Edit: seems to work if I first create the widgets, then go back and configure them:

for(1..6){
  $entries{$_}{'entry'} = $fr->Entry();
  $entries{$_}{'entry'}->configure(
    -textvariable    => \$entries{$_}{'addy'},
    -width           => 3,
#    -validate        => 'focusout',
#    -validatecommand => [ \&validate,$_,\%entries ],
#    -invalidcommand  => [ \&show_invalid,$entries{$_}{'entry'},$_ ],
  );
  $entries{$_}{'entry'}->pack(-side => 'left');

}

for(1..6){
$entries{$_}{'addy'} = 'zz'.$_ if($_ == 3);
  $entries{$_}{'entry'}->configure(
    -validate        => 'focusout',
    -validatecommand => [ \&validate,$_,\%entries ],
    -invalidcommand  => [ \&show_invalid,$entries{$_}{'entry'},$_ ],
  );
}
[download]

This might help you. It changes color, but dosn't flash. Also it helps to use 'any' for the validate method, rather than focusout. The key lines are

$mw->waitVisibility;                                  
$mw->after(100,sub{$entries{3}{'entry'}->focusForce});
[download]

Here is a working script that should show you the way of highlighting a textvariable which is invalid. You can perfect it yourself. :-)

#!/usr/bin/perl
use strict;
use warnings;
use Tk;

my $mw = MainWindow->new(-title => 'Mac Address Input Example');
my $fr = $mw->Frame()->pack(-expand => 1, -fill => 'both');
my $lb = $fr->Label(-text => 'MAC Address')->pack(-side => 'left');

my %entries;

for(1..6){
  $entries{$_}{'entry'} = $fr->Entry();
  $entries{$_}{'entry'}->configure(
    -textvariable    => \$entries{$_}{'addy'},
    -width           => 3,
#    -validate        => 'focusout',
#    -validatecommand => [ \&validate,$_,\%entries ],
#    -invalidcommand  => [ \&show_invalid,$entries{$_}{'entry'},$_ ],
  );
  $entries{$_}{'entry'}->pack(-side => 'left');

}

for(1..6){
$entries{$_}{'addy'} = 'zz'.$_ if($_ == 3);
  $entries{$_}{'entry'}->configure(
    #-validate        => 'focusout',
    -validate    => 'all',
    -validatecommand => [ \&validate,$_,\%entries ],
    -invalidcommand  => [ \&show_invalid,$entries{$_}{'entry'},$_ ],
  );
}

$mw->waitVisibility;
$mw->after(100,sub{$entries{3}{'entry'}->focusForce});

MainLoop();

# returns `1' if valid, and `0' if invalid
sub validate {
  my($num,$val) = @_;
  unless($val){ print "Field $num has nothing to validate\n";return 1;
+}

  my $valid = ($val =~ /^[0-9a-f]{1,2}$/i) ? 1 : 0;
  printf "Field %s, validating \`%s'...%s\n",$num,$val,$valid? "ok": "
+FAILED";

  return $valid;
}

sub show_invalid {
  my($widget) = @_;
#  print "@_\n";
  $widget->focus();

  # background of the problem field in red
  my $bg = $widget->cget('-bg');
  $widget->configure(-bg => 'lightpink');
  $widget->update();

}
[download]

---

I'm not really a human, but I play one on earth.
Old Perl Programmer Haiku ................... flash japh

Here is a working script that should show you the way of highlighting a textvariable which is invalid.

@zentara,

Thanks for this, will definitely check it out!

heh, lightpink should not be too hard to miss...

Edit:

zentara, I checked out your code, there are a couple problems. The first is; I think in your validate sub, you left off the 2nd argument ($ref), b/c in yours it is trying to validate a HASH, not the value in the field. Am I right there?

The second is; if I use 'all' instead of 'focusout' for -validate, then it breaks again - I can tab or click out of the bad field. Is there some other piece missing for 'all' to work properly?

Edit 2:

Here's an updated version that I'm now trying out. It seems to work okay. It incorporates zentara's suggestion of using 'all' vs 'focusout' (though I'm not sure how/why it is working correctly...)

Also, to get it to evaluate all pre-populated fields when the app first fires up, I'm using eventGenerate to auto-Tab thru all the fields. It will stop on the first bad field it encounters, by virtue of the fact that I disable all other Entry widgets, if a problem is discovered. Once the field is validated, the other fields are re-enabled.

This works, but it feels very hacky though...(the auto-tabbing and widget-disabling parts).

#!/usr/bin/perl
use strict;
use warnings;
use Tk;

my $mw = MainWindow->new(-title => 'Mac Address Input Example');
my $fr = $mw->Frame()->pack(-expand => 1, -fill => 'both');
my $lb = $fr->Label(-text => 'MAC Address')->pack(-side => 'left');

# widget used to display Entry field errors
my $errW = $fr->Label(-foreground=>'red')->pack(-side=>'bottom');

# hash to hold Entry widgets
my %entries;

# loop thru the number of Entry widgets desired
for(1..6){

  # create the Entry widget
  $entries{$_}{'entry'} = $fr->Entry(
    -textvariable => \$entries{$_}{'addy'},
    -width        => 3,
  );

  # save default widget background
  $entries{$_}{'bg'} = $entries{$_}{'entry'}->cget('-bg');

  # pack/display the widget
  $entries{$_}{'entry'}->pack(-side => 'left');

}

# loop back thru the created widgets
for(1..6){

  # put some bogus values in for testing...
  $entries{$_}{'addy'} = ($_>1) ? $_.$_ : '';
  $entries{$_}{'addy'} .= 'z' if($_ == 3 or $_ == 4);

  # configure the validation for the widget
  $entries{$_}{'entry'}->configure(
#    -validate        => 'focusout',
    -validate        => 'all',
    -validatecommand => [ \&validate,$_ ],
    -invalidcommand  => [ \&show_invalid,$entries{$_}{'entry'},$_ ],
  );
}

# put focus on initial Entry widget
$entries{1}{'entry'}->focus();

# auto-tab thru all Entry widgets to perform validation on pre-populat
+ed values
for(1..6){
  $mw->eventGenerate('<Tab>');
#  $mw->idletasks;
  $mw->after(100);
  $mw->update;
}

MainLoop();

sub clear_err {
  my($num) = @_;
  $errW->configure(-text=>'');
  $entries{$num}{'entry'}->configure(-bg=>$entries{$num}{'bg'});
}

# returns `1' if valid, and `0' if invalid
sub validate {
  my($num,$val) = @_;
  unless($val){ print "Field $num has nothing to validate\n";return 1;
+}

  my $valid = ($val =~ /^[0-9a-f]{1,2}$/i) ? 1 : 0;
  printf "Field %s, validating \`%s'...%s\n",$num,$val,$valid? "ok": "
+FAILED";

  if($valid){

    # clear error widget
    &clear_err($num);

    # re-enable all other widgets
    for(1..6){
      next if(/^$num$/);
      $entries{$_}{'entry'}->configure(-state=>'normal');
    }

  }else{

    # update the error widget with text indicating a problem with the 
+value
    $errW->configure(-text=>"Field $num value \`$val' is invalid");

  }

  return $valid;
}

sub show_invalid {
  my($widget,$num) = @_;
  $widget->focus();

  # turn the background of the problem field to red
  my $bg = $widget->cget('-bg');
  $widget->configure(-bg => 'red');
  $widget->update();

  # temporarily disable focus on all other widgets
  for(1..6){
    next if(/^$num$/);
    $entries{$_}{'entry'}->configure(-state=>'disabled');
  }

}
[download]

...that is what the code I borrowed had..

The road to Hell is paved with borrowed code:-).

The road to Hell is paved with borrowed code:-).

Then I'm building the Devil an 8-lane superhighway...

For all sleeping in tk apps gui frameworks use tk that gui framework timer functions, use Tk::after