Does not work with the current versions of Firefox, a fact not mentioned in the writeup.

It still doesn't work. Not on TB, or FF.

Not working on Linux since FF moved to Quantum ((FF57?)

Periodically stops working. Now, April 2018 it is not fixed for weeks ...
The wanhunglo fix mentioned below works!

The thunderbird version of this addon breaks regularly rendering TB unusable because of the tiny fonts. I URGE ANYONE TO GO https://bugzilla.mozilla.org/show_bug.cgi?id=1453928 REGISTER AND UPVOTE THE BUG/COMMENT SO THAT THUNDERBIRD ADDS A FONT INCREASE OPTION BY DEFAULT

Once again not working anymore, because the id!ot author has built in a 90 day time limit after which the addon silently fails. Change build date (unix timestamp) or remove the check function in line 1382 of bootstrap.js to make it work again. Or visit wanhunglo (dot) com to download a fixed version.

Why is this addon still listed? Reported several times, this sh!t has been happening for the past three "updates" every single time!

absolutely not working extension

No funciona desde la última gran actualización

Version 56, in Thunderbird 52.6.0 (64 bits) on MacOS shows no entry in tool menu neither it shows the button in the status bar. Thus, it cannot be opened !! Unusable :(

I'm using FF 52 and went as far back to v51 of this addon trying to find one that works. None did. Apart from the entry in the addon manager, there was no sign that it had installed - no toolbar option, no status bar icon. Nothing.

On Linux I can't change the font family.

Add on does not work with FF Quantum. All the advice I find on any of these pages involves files, extensions, changing this and that in your computer. You need to be a damn programmer to figure it out! Mozilla just create a simple easy to use and understand way for us to increase the size of the text in the Firefox menus. It was there before you can do it again. I have computer glasses and this is causing eye strain!!

It isn't working in the latest update of Firefox. FIX It already, millions of individuals with low vision depend on you

it doesn't work at all wih the latest t-bird. shame on Mozilla.

No longer works on current versions of Firefox.

A Call For Help ~ TFSC Needs to be Fixed or Remade - Don't give up on this Add-On

This is a sorely needed add-on that many many people have came to rely on. I'm not here to blame Baris for an add-on that doesn't work but to mention how by this time Mozilla should have come with an 'In Built' version of this TFSC function as PART of Firefox itself. It's hard to believe that after all of this time, and all the DREADED news of FF57 Quantum coming that Mozilla could have helped the plethora of users relying on this add-on as a FUNCTION of Firefox. In a way, Baris is getting thumped for an add-on function that so many ppl believe should be part of the Firefox 'Preferences' BY NOW being that so many relied on it to even see what they were doing here while using THIS browser. Shame on YOU Mozilla for not filling in to help this roll-out of FF57. Many of us are still hoping with all our might that Baris can restore this OR some other developer can aid by filling in where Baris left off. What the Hell happened here??? This is really such a sad situation for the 'Visually impaired' users & the folks who view their net viewing several feet back from their TV-Monitor to enjoy the internet.

All of the browser Text on tabs and ALL of the Menu text on drop downs were afftected making it one heck of s strain to use Firefox. So OUR hope is that someone HEARING our PLEA shines a light on this situation and either puts TFSC back to it's optimum function OR can get a fire built under Mozilla's butt to build this Function into Firefox itself. Please______

03-18-19 I still come in here 'hoping' that someone will pick up the ball & run with it in getting this add-on back into usefullness. FF57 was a long time ago.

author wants to install missing tools/add-ons but doesn't specify what. can't even use add-on without jumping through too many hoops.

how do i uninstall this?

I have used Theme and Font changer for years with Thunderbird and with all the updates Thuderbird fonts have gone extremely small as all are saying. Theme and font changer fixes this, but it wont save changes in my windows 7

Nothing working anymore since we got the last update (10 of january 2018) ! When i uninstall the addon and re-install it ,impossible to make this module working .....nothing happens !!!

Doesnt work...people like me who are getting older and eyes needing glasses...it seems you didnt take account of us when the 56 theme and font was great and now that wont even work. Firefox for every update makes your browser worse. Get some common sense and do it right.

What's always going on with these Baris Derin addons ?
Suddenly TFSC no longer works on TB

What's the latest version working on TB 52.5.2 ?
Where can I find old versions of Addons ?

It's a pity things are being messed up so frequently (partly initiated by Mozilla and it's Web-Extentions hype)

This is a great ad-on, when it is not being updated. It suddenly disappears from the toolbar menu, and all settings with it. So you have to go search for an update.

THIS time (Jan 8, 2018) it seems it's broken, and cannot be fixed.

Shoddy programming, really.

Unfortunately the mediafire version only worked for a day for me. I found the following on Mozilla support though and it worked fine for me:
(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button accepting the risk.

(2) In the filter box, type or paste pix and pause while the list is filtered

(3) Double-click layout.css.devPixelsPerPx and change its value to 1.25 and click OK, which corresponds to 125% font size in Windows display settings. The toolbar area should enlarge after a few moments. Too small? Try 1.5 and see whether that suits you better. And so on. If you are on Mac and use a Retina display, anything below 2.0 may be smaller than what you started with, so start with 2.0.