Its been awhile since I fiddled with this stuff, but I took a look at one of my expandable frame objects, see below code. I think the "-expand" parm to pack() is what you need.

my $table_frame = $mw->Frame
                      (-height=>'10',
                       -width=>'30',
                       -relief=>'groove',
                       -borderwidth=>'3'
                       )->pack(
                              -expand=>1,
                              -fill=>'both',
                              -pady=>'0'
                              );
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I think when you pack your widget into the frame, you also have to allow -expand option. Here is continuation of code that packed a scrolled TableMatrix into that frame. Scrolled doesn't have any thing to do with whether you can re-size or not, that is a separate idea.

$table = $table_frame->Scrolled('TableMatrix',
 -cols => scalar(@col_head),
 -rows =>16,  #fixed number of rows!!! need to grow this dynamically!
 -titlerows => 1,
 -variable => $tMain,
 -state => 'disabled',   # no direct editing of cells
 -resizeborders => 'col', 
 -bg => 'white',
 -rowheight => 1,  #make row display more compact....
 -bd => [0,1,0,1],
 -justify => 'left',
 -drawmode => 'compatible',
 -wrap => 0,
 -relief => 'solid',
 -scrollbars=>'se',
 -exportselection =>0,
)->pack(-expand =>1, -fill=>'both');
$table->rowHeight(0,2);  #varies height of title row (0)
$table->tagRow('title',0);
$table->tagConfigure('title', -bd=>2, -relief=>'raised');
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