Does work in Seamonkey 2.40 Rated 5 out of 5 stars

but not exactly like you expect. It's more like a window-mode where you have to drag the corner to fill the screen. Once you do that though, you are all set. No caption bar, and the taskbar still shows (Win7.) Then you can toggle the menu bar with alt, and gain a fair amount of screen space.

If you toggle f11 for full screen, usually the Win taskbar disappears and comes back like it should. Sometimes though, the whole default Windows7 border including the useless caption bar will come back and a restart is needed. Overall, I'll give it 5 stars because it does get rid of the caption bar, and HideCaptionTitlebarPlus doesn't so what else you gonna do?

Rated 1 out of 5 stars

In SeaMonkey 24, just made Menu bar bigger w/o hiding titlebar.

This review is for a previous version of the add-on (2.3.1-signed.1-let-fixed). 

Rated 5 out of 5 stars

Добавьте кнопку показать/спрятать заголовок. Это еще и решит проблему перетаскивания окна, когда нужно перетащить просто включаем заголовок.
И еще нужна опция которая в режиме "не на весь экран" показывает заголовок, то есть заголовок будет спрятан, только если пользователь включит режим "на весь экран".

This review is for a previous version of the add-on (2.3.1-signed.1-let-fixed). 

Can't drag window on xfce Rated 4 out of 5 stars

Very good! But! I can't drag window on xfce (Debian)
just only resize.
Please, fix

This review is for a previous version of the add-on (2.3.1-signed.1-let-fixed). 

Rated 5 out of 5 stars

Я как пользователь Linux был очень не доволен системными рамками вокруг ФФ, настолько что был переход на chrome (прада долго я не выдержал этого пожирателя RAM). Вам мой покон от всего сердца))

This review is for a previous version of the add-on (2.3.1-signed.1-let-fixed). 

Rated 4 out of 5 stars

Рабочее пространство действительно выигрывается. Это уместно даже на мониторах покрупней чем у нетбуков.

This review is for a previous version of the add-on (1.9.1-signed). 

Rated 3 out of 5 stars

does not work with 19.0 FF as of yet...

This review is for a previous version of the add-on (1.9.1-signed).  This user has a previous review of this add-on.

Try new version
https://addons.mozilla.org/ru/firefox/addon/no-caption/versions/2.0

Rated 1 out of 5 stars

My FF window's size has be resized at a small square, and I didn't have a choice to restore my FF.

I run with FF 17.0.3 ESR and my OS is WinXP SP2.

This review is for a previous version of the add-on (1.7.1-signed). 

Try new version
https://addons.mozilla.org/ru/firefox/addon/no-caption/versions/2.0

Thanks Rated 5 out of 5 stars

Works for me. This addon seems to be the only way to make Firefox under Linux hide the titlebar (not using KDE). This is why I give it five stars even though it has a little flaw: if you open enough tabs, the last one gets overlapped with the minimize, maximize and close buttons.

This review is for a previous version of the add-on (1.6.1-signed). 

thank you Rated 5 out of 5 stars

It's useful for me.

This review is for a previous version of the add-on (1.6.1-signed). 

Does the opposite Rated 1 out of 5 stars

This does not remove the title. Firefox removed the title in version 4. This extensions adds it back.
Maybe people looking at this extension would prefer: https://addons.mozilla.org/en-US/firefox/addon/tabs-always-in-titlebar/?src=search

This review is for a previous version of the add-on (1.4.1-signed).