Creating multi-select Dropdown Checkbox-list

I'm trying to create a Dropdown Checkbox-list which is very similar to this example.

Please, pay attention to the "Tags" section of Search Articles

http://www.codeproject.com/info/search.aspx

Additional to above features, I want to add an option "firstItemChecksAll" for each group i.e. select "All" for "Language, Platform, Technology, Audience..." etc.

If anyone have seen similar working examples on any websites or know how to code such Dropdown check-list using JavaScript/jQuery or even tutorials to recommend please let me know.

Thanks

p.s. I am aware of

http://code.google.com/p/dropdown-check-list/
http://www.givainc.com/labs/mcdropdo...ery_plugin.htm
http://easylistbox.com/demoMultiDropDown.aspx?rl=mf

but none of them fits what I want exactly so .....

The site uses Bubble Tooltips

Good tip to know.
I may be able to learn something from it.

Thank you, Fang :)