Does anybody have an example of a twin trigger component using EXT JS 4?

I'm working on upgrading an existing application from EXT JS 3.x and have been trying to figure this out by extending a combo box and using the thread: http://www.sencha.com/forum/showthre...rm.ComboBoxAdd, but I'm fairly new to EXT JS and am not really sure what I need.

Any help would be very welcome.

Thanks,

Paul.