my $display=$vbox->get_display;
my @list=($display->list_devices());
for(my $i=0;$i<$#list;$i++){
  my $name=$list[$i]->name;
    my $result=$list[$i]->set_mode('GDK_MODE_SCREEN');
    print "activating device \# $i, name=$name result=$result\n";
}
$drawing_area->set_extension_events("cursor");