function class_change(element, newclass ){
    if(element) element.className = newclass;
}

function set_current(element){
	var i = 0;
	while (i < categories.length){
        if (categories[i] == element.id) {
			categories.splice(i, 1);
		} else {
			i++;
		}
    };
	if(element.className == 'normal'){
		class_change(element, 'current');
		categories.push(element.id);
	} else {
		class_change(element, 'normal');
	};
	update_list()
	element.blur();
	return false;
}

function removeItems(array, item) {
	var i = 0;
	while (i < array.length) {
		if (array[i] == item) {
			array.splice(i, 1);
		} else {
			i++;
		}
	}
}

function update_list(){
	document.getElementById('selected_categories').value = '';
	for(i=0; i<categories.length; i++){
        document.getElementById('selected_categories').value += categories[i];
    };
}