Even I got the same result. But this seem to do the job: https://addons.mozilla.org/en-US/firefox/addon/hide-caption-titlebar-plus-sma/ https://addons.mozilla.o

Even I got the same result. But this seem to do the job: https://addons.mozilla.org/en-US/firefox/addon/hide-caption-titlebar-plus-sma/ https://addons.mozilla.org/en-US/firefox/addon/hide-caption-... Edit: aah got it. The OP mentioned that you have to use 'Nav bar on title bar' extension along with tree style tabs.