function findBy(container, property, value, all){
		var panels = $.data(container, 'accordion').panels;
		var pp = [];
		for(var i=0; i<panels.length; i++){
			var p = panels[i];
			if (property){
				if (p.panel('options')[property] == value){
					pp.push(p);
				}
			} else {
				if (p[0] == $(value)[0]){
					return i;
				}
			}
		}
		if (property){
			return all ? pp : (pp.length ? pp[0] : null);
		} else {
			return -1;
		}
	}
find a panel by specified property, return the panel object or panel index.