In addition to the idea of aligning your text to the upper left corner, you could put a newline(s) in your text, so that the "Send command XXXX\nto system YYYY" will clip the top line last. Also, you can declare your button text string before you build( or configure) the button, take the length of the text, and use the -width=>$length option. Think creatively. :-) You could also reconfigure your button text, whenever an resize takes place.

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

my $currentSize = $mw->reqwidth . "x" . $mw->reqheight;
$mw->bind( '<Configure>', [ \&OnResize, \$currentSize ] );

MainLoop;

sub OnResize {
    my ( $mw, $oldSize ) = @_;

    my $newSize = $mw->width . "x" . $mw->height;
    if ( $$oldSize ne $newSize ) {
## Resize has occurred do something: 
        printf( "Resize happened - old size: %s, new size: %s\n",
            $$oldSize, $newSize );
## set the old size to the new size 
        $$oldSize = $newSize;
    }
}
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