sub replace{

my $chosen="Label of button user clicked on";                             
  
  $t->insert('sel.first',"$chosen");              
  $t->delete('sel.first','sel.last');              
  $t->tagConfigure("rp",-foreground=>"black");

  my $r=$t->search(-forwards,"$chosen",'end');
  $t->tagAdd("rp","$r","$r wordend");
}
1;