var ajax = new Array();

function get_projects(cat_id) {
	var index = ajax.length;
	ajax[index] = new sack();	
	ajax[index].requestFile = '/ajax/get_projects_by_category.php?id='+cat_id;
	ajax[index].onCompletion = function(){ create_projects(cat_id, index) };
	ajax[index].runAJAX();
}

function create_projects(cat_id, index) {
	var obj = document.getElementById('category_' + cat_id);
	obj.innerHTML = ajax[index].response;
	obj.style.display = 'block';
}