Perl in a Nutshell, 2nd Edition

Geometry Managers

Creating widgets and determining how to display them are done with separate commands. You can create a widget with one of the widget creation methods (such as Button, Canvas, etc.), but you display them using a geometry manager. The three geometry managers are pack, grid, place, and form. pack is by far the most commonly used.

You can either pack a widget as you create it or create the widget object and pack it separately. For example, the previous “Hello World” example might have read:

#!/usr/bin/perl -w
use Tk;
my $mw = MainWindow->new;
$button = $mw->Button(-text => "Hello World!", -command =>sub{exit});
$button->pack;
MainLoop;