// javascript form checkbox handler
function handleCheckboxes( oFrm , prefix , mode ) {
	var i=0;
	var newval=false;
	var spattern = "^" + prefix + "\\[[0-9]+\\]$";
	for (i=0;i<oFrm.length;i++) {
		var c = oFrm[i];
		if (c.tagName!="INPUT") continue;
		if (c.type!="checkbox") continue;
		if (c.name.search( spattern )<0) continue;
		switch (mode) {
		case 1:	newval = true;break;
		case 0: newval = false;break;
		case -1: newval = !c.checked;break;
		}
		c.checked = newval;
	}
}	

function invertCheckboxes( oFrm , prefix ) { handleCheckboxes( oFrm , prefix , -1 ); }
function checkCheckboxes( oFrm , prefix ) { handleCheckboxes( oFrm , prefix , 1 ); }
function uncheckCheckboxes( oFrm , prefix ) { handleCheckboxes( oFrm , prefix , 0 ); }