use Tkx;
my $mw = Tkx::widget->new(".");
my $calc = $mw->new_ttk__button(-text=>"Calculate", -command=>sub {calculate();});
$calc->g_grid(-column=>1,-row=>3,-columnspan=>2,-sticky=>"ew");
$calc->g_bind("<Enter>",
 sub {$calc->configure(-background=>'red');});
Tkx::MainLoop();