HTML 5
http://code.google.com/p/box2dweb/downloads/list
http://www.html5cn.org/article-5149-1.html
http://www.html5cn.org/article-4978-1.html
http://www.codeproject.com/Articles/43074/WPF-Custom-ComboBox
http://www.codeproject.com/Articles/179149/Creating-a-Nullable-WPF-ComboBox
http://www.codeproject.com/Articles/14934/myComboBox
http://www.codeproject.com/Articles/42133/Multiple-Selection-ComboBox-for-Silverlight
http://www.codeproject.com/Tips/595936/Ownerdrawn-ComboBox-Example
http://www.codeproject.com/Articles/563862/Multi-Select-ComboBox-in-WPF
http://www.codeproject.com/Articles/187762/Tree-ComboBox-Control
http://www.codeproject.com/Articles/17502/Simple-Popup-Control