function change_focus(id, color) {
	if(document.getElementById('tr_'+id))
	    document.getElementById('tr_'+id).style.backgroundColor = color;
}

function isNumber(value){
    var numericExpression = /^[0-9]+$/
    if(value.match(numericExpression))
        return true;
    else
        return false;   
}

function addClassName(el, sClassName) {
	var s = el.className;
	var p = s.split(" ");
	var l = p.length;
	for (var i = 0; i < l; i++) {
		if (p[i] == sClassName)
			return;
	}
	p[p.length] = sClassName;
	el.className = p.join(" ").replace( /(^\s+)|(\s+$)/g, "" );
}

function removeClassName(el, sClassName) {
	var s = el.className;
	var p = s.split(" ");
	var np = [];
	var l = p.length;
	var j = 0;
	for (var i = 0; i < l; i++) {
		if (p[i] != sClassName)
			np[j++] = p[i];
	}
	el.className = np.join(" ").replace( /(^\s+)|(\s+$)/g, "" );
}