extend the web controls in c#

I am developing the menu webpart using the asp.net Menu control in user control page for sharepoint 2010. I want to make available properties and methods of menu to developer (API). SO i need to either override all the menu control members in custom class which extends Menu. but it is not abstract control right? so how i can do this? How i can make avail开发者_运维问答able to developers to extend the menu control ? is i need to write extension methods for menu control ? please guide. I am using VS 2010 with 3.5 framework.

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