This comes up all the time, you have an element, and you want to select it to be the sole active element from among it’s siblings. With jQuery that is simple enough:
element.addClass("active").siblings().removeClass("active")
Though it is not as simple as it can be and it also fails to chain well. The solution is a super simple jQuery plugin:
(($) -> $.fn.takeClass = (name) -> this.addClass(name).siblings().removeClass(name) return this )(jQuery)
Now you can really go nuts!
newElement.appendTo(layerSelect).takeClass("active").find(".name").mousedown()