sub btnpress {

my $btn = shift;

if($btn eq 'C') {

   $display  = '';
   $buffer   = '';
   $dbuffer  = '';
} 

if( $btn =~/F0/ ) { 
$display = sprintf "0 - Lights On", $dbuffer;
$mw->bind('<ButtonPress-1>', \&one);
} else {  
display($btn);
}
}

sub one {
$display = sprintf "0 - Lights Off", $dbuffer;
}