I'm building an app with TK and need a way to dynamically change the contents of the main window. My approach is to place a frame in the window that takes up all of the space, then use subs to clear and fill the frame. When I try this, however, the sub isn't doing anything. here is my code: 
use warnings;
use strict;

use Tk;

### Build Main Window #
my $mainWindow = MainWindow->new;
$mainWindow->title("BNS Cable Customer Managment");
$mainWindow->geometry("800x600");


### Build Menu Bar
my $mainMenu =$mainWindow -> Menu();
$mainWindow -> configure(-menu => $mainMenu);

my $fileM = $mainMenu -> cascade(-label=>"File", -underline=>0, -tearo
+ff => 0);
my $optsM = $mainMenu -> cascade(-label=>"Options", -underline=>0, -te
+aroff => 0);
my $modeM = $mainMenu -> cascade(-label=>"Mode", -underline=>0, -tearo
+ff => 0);


##File Menu
$fileM -> command(-label => "New Property", -underline=>0 );
$fileM -> command(-label => "Logout", -underline=>0 );
$fileM -> separator();
$fileM -> command(-label =>"Exit", -underline => 1,
                      -command => sub { exit } );

##Options menu
$optsM -> command(-label => "Preferences", -underline=>0 );


##Mode Menu
$modeM -> command(-label => "Property Centric",
                  -underline=>0,
                  -command => \&propCen);
                  
$modeM -> command(-label => "Task Centric", -underline=>0 );


#### Now the main Content
my $content = $mainWindow->Frame;
$content->pack(-fill => 'both',
                -expand => 1,
                -pady => 10,
                -padx => 10);

MainLoop;


sub propCen {

$content->packForget;
 my $propList = $content->Scrolled("Listbox",
                                  -scrollbars=>"e",
                                  -exportselection => 0,
                                  -selectmode => "extended")
                                     ->pack( -anchor => 'w',
                                             -fill => 'y',
                                             -expand => 1);
}

[download]
If I move the contents of the sub out and into the mainloop, it displays as I want it to.
nevermind..... I wasn't repacking the frame after I 'forgot' it. Saw that as soon as I posted.

While that did work, It's not working as expected.
With that code, the proper contents load correctly, but if I call the sub multiple times in a row, it starts nesting the widgets, instead of destroying and rebuilding.
Am I missing something or is there a better way to go about this?

In reply to passing TK object into a sub by vortmax

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