Eureka! Rated 5 out of 5 stars
Close-tab buttons show up, the tab bar is resizeable, tabs can be reordered by dragging them and I'm able to drag and drop links onto the tab bar. Seems to play well with Tab Mix Plus. The "New tab" button doesn't show up (a Tab Mix Plus option), but double-clicking on the tab bar opens a new tab. I can finally ditch the userChrome hack. A huge THANK YOU to Tee Yen Ng!