I'm not entirely sure what you're asking. If you want Perl/Tk to redraw a widget (that you've changed somehow behind the scenes), just do this:

     $widget->update();
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If you're processing and want Tk to be responsive (redraws, respond to events, etc...) during that processing, then call idletasks on the top-level widget in your processing loop:

     $mainwindow->idletasks();
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