$f_dialog->Label (-text => 'Search Query')->pack(-side=>'left');
my $e_search =$f_dialog->Entry (-textvariable => \$tv_search_command,)->pack(-side=>'left');
$e_search->bind("<Return>", sub {enter_pressed();} );

......
sub enter_pressed()
{
  #first few lines of this sub...
  $text->delete("1.0", 'end'); #Update 000ops this is for another window
                         #not needed for entry window
                         #I think text visible to user entry gets
                         #cleared by the time we are here.
                         #I do think making a copy of entered text for
                         #further processing is good idea though...
   my $search_command = $tv_search_command;
....blah
}