[Linux] Add an option for non native titlebar buttons.

[WeatherTheFoxer]

Currently, Firefox does not have a feature to use non native titlebar buttons from GTK or Qt Themes.
This would greatly improve theming support.

[Jon]

Thanks for submitting an idea to the Mozilla Connect community! Your idea is now open to votes (aka kudos) and comments.

[John14]

Isn't the Customize toolbar... and then ticking (checking) or unticking (unchecking) the "Title Bar" checkbox doing exactly that?