$ perl -MTk -le " $_= Tk->findINC( 'demos/widget_lib' ) ; s!/!\\!g ; print "
C:\perl\site\5.12.2\lib\MSWin32-x86-multi-thread\Tk\demos\widget_lib

$ cd /d C:\perl\site\5.12.2\lib\MSWin32-x86-multi-thread\Tk\demos\widget_lib

$ grep -ri textvariable .
./entry3.pl:        -textvariable    => \$e3_var,
./floor.pl:                         -textvariable/ => \$floor::current_room);
./image2.pl:    my $dir_name = $TOP->Entry(-width => 30, -textvariable => \$demo_img);
./keysyms.pl:    $mw->Label( qw/ -relief solid -width 20 /, -textvariable => \my $k )->pack;
./labframe.pl:$f->LabEntry(-label => "Testing", -textvariable => \$test)->pack;
./mega.pl:Here's an excerpt from a Text dervived mega-widget called TraceText; you can examine the complete code in another demonstration. This widget defines its content using a new -textvariable option.
./mega.pl:            -textvariable => 'METHOD', 'textVariable', 'TextVariable', undef,
./mega.pl:    sub textvariable {
./mega.pl:    } # end textvariable
./mega.pl:Tk::TraceText::Populate defines the -textvariable option and provides a private method to establish the watchpoint. In Perl/Tk, all mega-widget options are specified via a ConfigSpecs() call, named after the C structure.
./mega.pl:Briefly, ConfigSpecs() names options and tells Perl/Tk what to do when one is specified on a configure() or cget() call. It also specifies the option's database name, class name and default value for option DB lookups. For our -textvariable option, the Perl/Tk framework invokes a METHOD (subroutine) by the same name as the option, minus the dash, of course. Other choices include CHILDREN, DECENDENTS, a name (or list of names) of a subwidget, etcetera.
./menbut.pl:        -textvariable       => $varref,
./menus.pl:        -font => 'Helvetica 10', -textvariable => \$status_bar)->
./menus2.pl:        -font => 'Helvetica 10', -textvariable => \$status_bar)->
./notebook.pl:       -textvariable => \$name)->pack(-side => "top", -anchor => "nw");
./notebook.pl:       -textvariable => \$email)->pack(-side => "top", -anchor => "nw");
./notebook.pl:       -textvariable => \$os)->pack(-side => "top", -anchor => "nw");
./Plot.pm:        -textvariable => \$pinfo{'prcmd'},
./search.pl:        -textvariable => \$file_name)->pack(qw/-side left/);
./search.pl:        -textvariable => \$search_string)->pack(qw/-side left/);
./showVars.pl:  my $w_i_value = $w_i->Label(-textvariable => \${$i});
./trace2.pl:        -textvariable => [ 'METHOD', 'textVariable', 'TextVariable', undef ],
./trace2.pl:sub textvariable {
./trace2.pl:} # end textvariable
./trace2.pl:    my $tt = $mw->Scrolled( 'TraceText', -textvariable => \my $frog )->grid;
./trace2.pl:just like a B<Text> widget.  Additionally, B<TraceText> adds a -textvariable
./trace2.pl:=item B<-textvariable>
./trace2.pl: my $tt = $mw->TraceText( -textvariable => \$scalar );
./twind.pl:        -textvariable => \$embToggle,