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Firefox asking to be made the default browser again and again

Linux

Firefox on Linux can develop the habit to (rather randomly) ask again and again to be made the default browser. E.g. when started from Thunderbird by clicking a link it asks but when starting from a shell all is fine.

The reason to this is often two (or more) .desktop entries competing with each other.

So, walkthrough: (GOTO 10 in case you are sure to have all the basics right)

update-alternatives --display x-www-browser
update-alternatives --display gnome-www-browser

should both show firefox for you. If not

update-alternatives --config <entry>

the entry to fix the preference on /usr/bin/firefox.

Check (where available)

exo-preferred-applications

that the "Internet Browser" is "Firefox".

Check (where available)

xfce4-mime-settings

that anything containing "html" points to Firefox (or is left at a non-user set default).

Check (where available)

xdg-settings get default-web-browser

that you get firefox.desktop. If not run

xdg-settings check default-web-browser firefox.desktop

If you are running Gnome, check

xdg-settings get default-url-scheme-handler http

and the same for https.

LABEL 10:

Run

sensible-editor ~/.config/mimeapps.list

and remove all entries that contain something like userapp-Firefox-<random>.desktop.

Run

find ~/.local/share/applications -iname "userapp-firefox*.desktop"

and delete these files or move them away.

Done.

Once you have it working again consider disabling the option for Firefox to check whether it is the default browser. Because it will otherwise create those pesky userapp-Firefox-<random>.desktop files again.

Configuring Linux is easy, innit?

Thunderbird startup hang (hint: Add-Ons)

Debian

If you see Thunderbird hanging during startup for a minute and then continuing to load fine, you are probably running into an issue similar to what I saw when Debian migrated Icedove back to the "official" Mozilla Thunderbird branding and changed ~/.icedove to ~/.thunderbird in the process (one symlinked to the other).

Looking at the console log (=start Thunderbird from a terminal so you see its messages), I got:

console.log: foxclocks.bootstrap._loadIntoWindow(): got xul-overlay-merged - waiting for overlay-loaded
[.. one minute delay ..]
console.log: foxclocks.bootstrap._windowListener(): got window load chrome://global/content/commonDialog.xul

Stracing confirms it hangs because Thunderbird loops waiting for a FUTEX until that apparently gets kicked by a XUL core timeout.
(Thanks for defensive programming folks!)

So in my case uninstalling the Add-On Foxclocks easily solved the problem.

I assume other Thunderbird Add-Ons may cause the same issue, hence the more generic description above.

Mozilla Firefox and Thunderbird Menu font sizes

Open Source

The font size Mozilla chose for Firefox and Thunderbird menus looks awfully large on Netbook screens. It wastes space and is visually at odds with reasonably sized content. And for some weird reason you can set the content font and size via the menu but not the font and size for the drop-down menus themselves.

As the "Theme Font & Size Changer" Add-On doesn't work reliably and phones home way too often (showing a nag screen), I dug back into how to do this "manually". Probably a decade after I fixed this the first time...

You need to create the file ~/.mozilla/firefox/*/chrome/userChrome.css with * being your profile directory (<random_number>.default usually) and you most probably have to create the chrome directory first.

The same for Thunderbird resides in ~/.thunderbird/*/chrome/userChrome.css. Here again the chrome directory will most probably need to be created first.


/* Global UI font */
* { font-size: 10pt !important;
  font-family: Ubuntu !important;
}
 

needs to go into these files for Firefox or Thunderbird respectively. The curly braces are important. So copy & paste correctly. Symlinks or hardlinks are fine if those files do not need to differ between your web browser and your email client.

Restart Firefox and/or Thunderbird to see the effect.

Obviously you can choose any other font and font size in the snippet above to suit your taste and requirements.

If you are massively space-confined and don't mind a quite ugly UI, check out the Littlefox Add-on. Ugly but optimal use of the minimal screen estate with very small screens.