$ perl -wMstrict -MTk
my $mw = tkinit;
my $lb = $mw->Scrolled( "Listbox", -background => "red" )->pack;

$lb->Subwidget("xscrollbar")->configure(
    -background => "blue", 
    -activebackground => "blue",
    -troughcolor => "blue",
);
MainLoop;