function showHideBlock (block){
	var obj = document.getElementById (block) ;
	if(obj)obj.style.display = (obj.style.display == 'none' ) ? 'block' :  'none' ;
}




// preload images
function preloadImages(imgArr){
	if (document.images) {
		var preloaded = new Array ();
		for (var i=0; i<imgArr.length;i++) {
			preloaded[i] = new Image () ;
			preloaded[i].src  = imgArr[i];
		}
	}
}

// test forms
function testForm (ref){
	
	
	var f = document[ref] ;
	var cond , valname;
	for (var i = 0 ; i < allforms[ref].length ; i += 2 ) {
		valname =  (f[allforms[ref][i]].type.indexOf('select') > -1) ? '' : '.value'  ;
		cond = allforms[ref][i+1][0].replace (/value/g , "f." + allforms[ref][i] + valname);

		if (!eval (cond)){
			alert (allforms[ref][i+1][1]);
			return false ;
		}
	}
	return true ;
}

function is_email(str) {
	var str = trim (str) ;
	if (str.indexOf(" ") != -1){
		return false;
	}else if (str.indexOf("@") == -1){
		return false;
	}else if (str.indexOf("@") == 0){
		return false;
	}else if (str.indexOf("@") == (str.length-1)){
		return false;
	}
	var arrayString = str.split("@");
	if (arrayString[1].indexOf(".") == -1){
		return false;
	}else if (arrayString[1].indexOf(".") == 0){
		return false;
	}else if (arrayString[1].charAt(arrayString[1].length-1) == ".") {
		return false;
	}
	return true;
}

function trim (str){
	return str.replace(/^\s*|\s*$/g,"") ;
}

function swapCatImage (block){
	var obj = document.getElementById (block) ;
	if(obj)document.getElementById ('img'+block).className = (obj.style.display == 'none' ) ? 'linkcat_parent' :  'linkcat_parent_open' ;
	
}