This brings up a good point, what do YOU expect to happen when you press a <control s> in the TextUndo widget? The normal behavior, on my Tk ( version Tk-804.029_500 ) , with no extra bindings associated with it, is to print what appears to be an underscore line segment, not a newline. It is not a dash or hyphen. Repeated presses of <control s> create a continuous line looking like an underscore (at the bottom of the font area).

Do you want this behaviour?

If you want to stop all text insertion, with a <control s>, try this and see what happens. I get NO insertion of any kind into the TextUndo widget. Notice I'm getting the REAL widget, not the Scrolled one.

#!/usr/bin/perl
use warnings;
use strict;
use Tk;
require Tk::TextUndo;

# a <control s> in the TextUndo widget produces
# nothing in the Text area, and a foo to the console

my $mw = tkinit;

# create a top bar for testing pure $mw focus
my $button = $mw->Button(-text=>'test')->pack();

$mw->bind('<Control-s>', sub { print "main control s \n" });

my $t = $mw->Scrolled ('TextUndo')->pack;
my $t1 = $t->Subwidget("scrolled"); # get real widget

$t1->bind('<Control-s>', sub { print "\t\tfoo\n"; $_[0]->break });
$t1->bindtags([($t1->bindtags)[1,0,2,3]]);

MainLoop;
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To address the point that you saw no difference in binding to a Scrolled or standard TextUndo widget, notice the difference in behavior in this script, where I bind to the Scrolled widget. I get the foo to the console, plus the underscore line gets printed to the TextUndo.

#!/usr/bin/perl
use warnings;
use strict;
use Tk;
require Tk::TextUndo;

# when binding to the Scrolled widget, instead
# of the real widget, a line gets printed to the text area
# as well as the foo to the console

my $mw = tkinit;

# create a top bar for testing pure $mw focus
my $button = $mw->Button(-text=>'test')->pack();

$mw->bind('<Control-s>', sub { print "main control s \n" });

my $t1 = $mw->Scrolled ('TextUndo')->pack;

$t1->bind('<Control-s>', sub { print "\t\tfoo\n"; $_[0]->break });
$t1->bindtags([($t1->bindtags)[1,0,2,3]]);

MainLoop;
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