WPF ComboBox ControlTemplate

I want to create a WPF ComboBox that contains buttons on the right side near the drop-down button, like the Firefox 3 address bar (which has the Favorites button, RSS subscribe button, etc.). The ComboBox needs to be editable (in xaml: IsEditable=True). To achieve this, I tried to create my own custom ControlTemplate, but it didn't work (I never seemed to be able to open the combo's drop down). Any idea? ControlTemplate sample?

Thanks,
Orr