In functions/widgets.php::get_display_field(...) for 'popup' and 'popup2'
widgets, consider removing the following code:

// assume http:// prefix if not absolute.
if(!is_url_absolute($value) && !file_exists($value))
{
	$value = 'http://'.$value;
}

... and even replacing:

if(!is_url_absolute($value) && !file_exists($value))
{
	// do not display a field in this case.
	return '';
}

