var _POPUP_FEATURES = 'location=0, statusbar=0,	menubar=0, width={w}, height={h}, scrollbars=yes';

function raw_popup(url, target, features){
	var _w = 650;
	var _h = 650;
	if(screen.width < _w) { _w = screen.width-50; }
	if(screen.height < _h) { _h = screen.height-50; }
	if(isUndefined(features)){
		features = _POPUP_FEATURES.replace("{w}",_w).replace("{h}",_h);
	}
	if(isUndefined(target)){
		target = '_blank';
	}
	var theWindow = window.open(url,target,features);
	theWindow.focus();
	return theWindow;
}

function link_popup(src){
	return raw_popup(src.getAttribute('href'), src.getAttribute('target') || '_blank', "");
}

function image_popup(src, features){
	return raw_popup(src.getAttribute('href'), src.getAttribute('target') || '_blank', features);
}

function isUndefined(a) { return typeof a == 'undefined' }

function prepare_field(fld, str){
	if(fld.value == str){
		fld.value = "";
	}
}