P.S. The reason your Button-1-Release dosn't work, is because you are NOT in the $mw when you do a resize, you are doing a WINDOWMANAGER event. So you have to realize your mouse is not in the Tk window anymore, during a resize.

#!/usr/bin/perl
use warnings;
use strict;
use Tk;
my $mw = new MainWindow;

my $current_size = $mw->reqwidth . "x" . $mw->reqheight;
my $old_current_size = $current_size;

my $canvas = $mw->Canvas(-width => 300, -height => 300,
                -bg => 'black',
       )->pack();

$mw->bind( '<Configure>', sub{ &OnResize });

my $leave = 0;

$mw->bind( '<Leave>',sub { 
           $leave = 1; 
} );

$mw->bind( '<Enter>',sub { $leave = 0; 
                           &OnResize;
             } );


$mw->bind( '<3>',sub { 
        print "1\n";
        my $width = $mw->width - 10;
        my $height = $mw->height - 10;;
           $canvas->configure(-width=> $width, -height => $height);
           $mw->update;
         } );


MainLoop;

sub OnResize {
      
    my $current_size = $mw->width . "x" . $mw->height;
    if( $leave == 1) {return }
    if($old_current_size eq $current_size){return}

     ## Resize has occurred do something:
     printf( "Resize happened - old size: %s, new size: %s\n",
                             $old_current_size, $current_size );
    ## set the old size to the new size
    $old_current_size = $current_size;
}
[download]

I had the same issue today and found this thread. Yes, it is old, but I would like to add another solution in case someone needs it.

You can use a timer to wait for a moment before you do the resize. Cancel the timer if the MainWindow resizes again within a certain time and start it anew.

Sample code:

#!perl

use strict;
use warnings;
use Tk;
use v5.16;

# Skript zum manuellen resizen der Canvas nach Änderung der Größe des 
+MainWindow.
# Man muss nochmal einen Rechtsklick machen.
# Quelle: https://www.perlmonks.org/bare/?node_id=581309, abgerufen 20
+20-11-21


my $mw = Tk::MainWindow->new;

my $current_size = $mw->reqwidth . "x" . $mw->reqheight;
my $old_current_size = $current_size;

my $canvas = $mw->Canvas(
    -width => 300,
    -height => 300,
    -bg => 'black',
)->pack();

$canvas->update; # important to call this before binding <configure> e
+vent

my $after_resize_timer_id;
$mw->bind('<Configure>' => sub {
    say "MW resized";
    
    # reset timer again, if it was set
    $mw->afterCancel($after_resize_timer_id) if defined $after_resize_
+timer_id;
    
    # set timer
    # if MW doesn't resize again within a second or so, resize Canvas
    # if it does, reset timer to wait for a second or so
    $after_resize_timer_id = $mw->after(500, sub{
        say "Update canvas";
        my $width = $mw->width;
        my $height = $mw->height;
        $canvas->configure(-width => $width, -height => $height);
        $canvas->update;
    });
    
});

$mw->MainLoop;
exit(0);
[download]

    I have not managed to do that, using bindings to `Configure' and `ButtonRelease-1'.

In what way has it failed?  Please show the program you're using (or, if it's large, please show the smallest subset of the program that still demonstrates the problem).

It will also help to say how exactly it's failing; ie. what results you're getting, in contrast to what results you'd like to get.

The reason we need to know the results you're getting is that your program may not be failing for everyone who tries it.

The reason we need to know what results you'd like to get is that, without those, how can we know when we've achieved "success"?