In our code (formerly based on prototype), we do a lot of dynamic DOM creation. Many times we do not attach the created elements to the document until later in the code. This presents a problem when working with your library as your functions depend on YAHOO.ext.Element.get which requires the element to be appended to the document. I cannot think of any reason why you require this. I have created a patch that will allow the passing of an element that is not appended to the document. From my testing, it breaks nothing. I tried to maintain backwards compatibility. My changes are marked with comments.

I would appreciate it if you would test it, and if it meets your expectations, commit it to subversion. Thanks!

Code:
YAHOO.ext.Element.get = function(){
    var doc = document; 
    var docEl;
    var E = YAHOO.ext.Element;
    var D = YAHOO.util.Dom;
    
    return function(el){
        if(!el){ return null; }
        if(el instanceof E){
            if(el != docEl){
                    /*
		             * if getElementById is ull, use el.dom
		             */
                                var domElem = doc.getElementById(el.id);
				el.dom = (domElem)?domElem:el.dom;
                E.cache[el.id] = el; 
            }
            return el;
        }else if(el.isComposite){
            return el;
        }else if(el instanceof Array){
            return E.select(el);
        }else if(el == doc){
            
            if(!docEl){
                var f = function(){};
                f.prototype = E.prototype;
                docEl = new f();
                docEl.dom = doc;
            }
            return docEl;
        }
        var key = el;
        if(typeof el != 'string'){ 
            D.generateId(el, 'elgen-');
            key = el.id;
        }
        var element = E.cache[key];
        if(!element){
            /*
             * pass el instead of key. YAHOO.ext.Element will handle it.  You don't need to pass it key.
             */
			element = new E(el);			
            if(!element.dom) return null;
            E.cache[key] = element;
        }else{
            element.dom = doc.getElementById(key);
        }
        return element;
    };
}();