Here's an example that keeps the pointer locked inside a label widget. Hopefully this is closer to what you were asking for. You'll have to fill in getting the x/y coordinates for the event from Tk::bind and warping the pointer to a sensible spot

You may also want to have a look at Tk::grab. You can maintain the focus for keyboard traversal without confining the pointer, if this is useful.

Familiarize yourself with keyboard control of focus before you run this :)

#!/usr/bin/perl
use Tk;
use strict;
my $m=Tk::MainWindow->new();
# create a big label so that the window is large
# enough to demonstrate this
my $label=$m->Label(-bd => 5, -relief => "ridge",
         -text => "Label Text Here\n" x 10)->pack();
#
# bind Leave events from the label to 
# generate a useless virtual
# event. 
# (We don't really need to fire an event
# , we just need the warp option)
# Without the -x/-y options, it warps 
# the pointer to the nw corner of the widget
#
$label->bind('<Leave>', sub { 
           my($w)=shift;
           $w->eventGenerate('<<Not Used>>', -warp => 1);
       }
);
MainLoop;
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