How to Customize Firefox’s User Interface With userChrome.css

Today I read How to Customize Firefox’s User Interface With userChrome.css. You may need to enable with e.g. Firefox 69: userChrome.css and userContent.css disabled by default. If you change userContent.css you need to open your page in a new tab to force an update. I would guess that if you change userChrome.css you will need to restart Firefox (I don’t know I’ve only been using userContent.css).

I should be clear: there are two files: userChrome.css (which affects Firefox features like toolbars and tabs etc) and userContent.css (which affects web pages loaded in Firefox).

I’ve been using userContent.css to fixup CSS on various websites. You can limit your changes to a particular domain in this way:

/* 2020-07-01 jj5 - SEE: */
@-moz-document domain( {
  a:visited { color: purple !important; }

A folder named ~/.cache/kioexec/krun/13821_0/ already exists

2017-12-09 jj5 – TODO: document this on my blog…

On Debian GNU/Linux 9.1 (stretch) when I try to open an *.desktop (application/x-desktop) link in a browser I get:

A folder named ~/.cache/kioexec/krun/13821_0/ already exists.

Searching for:

A folder named kioexec krun already exists

turned up diddly squat.

I solved the issue (for me) by changing:

System Settings -> Personalization -> Applications -> Default Application s-> Web Browser


Open http and https URLs in an application based on the contents of the URL


Open http and https URLs in the following browser: firefox

How to open the current page in a new Firefox window

You can press Ctrl+N to open a new window, but the new window loads with your home page. What I’ve found myself wanting to do is to open a copy of the current page in a new window. The way I figured was to click History in the menu bar and then Shift+Click to load the page on the top of the list (assuming the page you want is actually on the top of the list… if that’s not what you want keep looking down the list!).

Fixing Firefox/Iceweasel restricted port

Today I ran into this warning from iceweasel when I tried to access a web service on port 101:

This address is restricted

This address uses a network port which is normally used for purposes other than Web browsing. Iceweasel has canceled the request for your protection.

I found this article which said:

  • Open about:config
  • Create if it’s not there
  • Set that setting as, e.g.: 101-104
  • Refresh the page

Adding ‘Attach to Icedove’ desktop/dolphin menu item on Debian Jessie

On Debian Jessie (testing) the default ‘Send as Email Attachment’ context menu item uses KMail, and only KMail, even if you’ve configured your desktop to use Icedove (Thunderbird) as your default mail client.

So you can remove the broken ‘Send as Email Attachment’ from Dolphin by opening Dolphin then:

Settings -> Configure Dolphin… -> Services -> uncheck ‘Send as Email Attachment’

Then to create a replacement feature that uses Icedove edit:


And enter:

[Desktop Entry]

[Desktop Action attachToEmail]
Exec=icedove -compose "attachment='$(echo %F | sed 's/\\ \\//,\\/\\//g')'"

Name=Attach to Icedove
Name[it]=Invia E-mail con Icedove
Name[es]=Enviar adjunto con Icedove
Name[de]=Als Anhang mit Icedove verschicken
Name[pt]=Anexar ao Icedove E-mail
Name[pt_BR]=Enviar arquivo(s) como anexo(s)
Name[fr]=Envoyer avec Icedove
Name[nl]=Voeg toe als bijlage aan Icedove
Name[pl]=Wyślij jako załącznik Icedove
Name[ru]=Отправить с помощью Icedove
Name[cz]=Odeslat jako přílohu Icedove


And make sure your .desktop file is executable:

 $ chmod +x ~/.kde/share/kd4/share/icedove_attachment.desktop