{
   package UI;
   ...
   sub refresh_track_display {}
   ...
}

{
   package UI::Graphical;
   our @ISA = 'UI';
   ...
   sub refresh_track_display {
      ...
   }
   ...
}

{
   package UI::Text;
   our @ISA = 'UI';
   ...
   # Inherit no-op refresh_track_display.
   ...
}

...
$ui->refresh_track_display();
...