"relief buttons in navigation toolbar" has no effect for some extensions buttons

[antistress]

Hi,

Having different extensions buttons : Cookie Monster, uBlock Origin, IPFlood [1] and UserAgent Switcher [2],
the "relief buttons in navigation toolbar" fuinctionnality works well with Cookie Monster & uBlock Origin buttons but has no effect on IPFlood & UserAgent Switcher buttons

I'm running Firefox 45.0.2 ESR on Debian testing & GNOME Theme Tweak 42.1

Thanks !

[1] http://ipflood.paulds.fr/
[2] http://chrispederick.com/work/user-agent-switcher/