...snip...
my $mw = Tkx::widget->new(".");
  $mw->g_wm_title("Jobs Not Forecasted");
    Tkx::button(".b",
        -text => "18-Letters",
        -background => "red",
        -width => 11,
	-command => sub { print "18L\n"; Tkx::i::call( ".b", "configure", "-background", "blue" ); }
},
    );
    Tkx::pack(".b");
...snip...