/// @desc open an "add to lighbox" window with a list of file IDs
function AddCheckedFilesToLighbox(formName, fieldName){
	fileIDs = '';
	fileIDFields = document[formName][fieldName];
	for (i=0; i<fileIDFields.length; ++i){
		if ( fileIDFields[i].checked ){
			if ( fileIDs.length ){
				fileIDs += ',';
			}
			fileIDs += fileIDFields[i].value;
		}
	}
	window.open('popup_add_to_lightbox.php?DontRedirect=1&id='+fileIDs,
		'Popup', 'scrollbars=yes,width=400,height=500');
}