function removeprefix(prefix,st) {
	if (prefix && st.indexOf(prefix) == 0) return(st.substr(prefix.length));
	return(st);
}

function countValueChars(field, count_field, limit, suffix) {
	field = $(field);
	count_field = $(count_field);
	if (field.value.length > limit) {
		field.value = field.value.substring(0, limit); 
		count_field.value = '0' + suffix;
	} else count_field.value = (limit - field.value.length) + suffix;
}

function overlay(url, frm) {
        if ($('overlay')) Element.remove('overlay');
        if (url) {
		post = frm ? $(frm).serialize() : '';
                new Ajax.Updater('body',url,{insertion: Insertion.Top,
                        onComplete: function(transport) {
			Effect.Appear('overlay');
		}, postBody: post});
        }
}
 
function select_checks(frm, name, action){
	inputs = $(frm).getInputs('checkbox',name);
	for (i=0;i<inputs.length;i++) inputs[i].checked = action;
}


function clean_radios(frm, name){
	inputs = $(frm).getInputs('radio',name);
	for (i=0;i<inputs.length;i++) inputs[i].checked = false;
}



function select_all_check(){
	for (i=0;i<document.matrix_index.elements.length;i++)
	if(document.matrix_index.elements[i].type == "checkbox")	document.matrix_index.elements[i].checked=1
}