So I have installed Firefox Developer Edition and placed it in /opt/firefox. I also created a related firefoxDeveloperEdition.desktop in /usr/share/applications that I have altered the Icon property to specify the icon of my preference. This sets the icon in the system's application and system launcher as expected and desired. However, in the dash it remains the same. Additionally, when opening Firefox Developer Edition it asks me if I want to set it to be my default browser. Agreeing to this creates another .desktop file, only this time in ~/.local/share/applications. This does not alter the icon in launcher / applications. Editing it there to change the Icon field does not update the dock. Of note, in /opt/firefox/browser/chrome/icons/default there are a few icons e.g. default-128.png which appears like the icon in the dock. However, I can not find a configuration file to fix this. Please advise.

  • WM_Class of your developper edition is probably the same as that of your regular version.
    – vanadium
    Feb 25, 2022 at 17:17
  • What does that mean exactly @vanadium?
    – SumNeuron
    Feb 25, 2022 at 19:01

1 Answer 1


For running applications, the icon in the dock is differentiated according to the WM_CLASS property of the window. My guess is that your Firefox Developer Edition runs with the same window class as the regular Firefox, i.e. "Navigator", "Firefox".

You need to start Firefox adopting a different WM_CLASS, and you need to tell the launcher to associate the icon with that WM_CLASS. Edit the .desktop launcher of Firefox Developer Edition to:

1 Start Firefox adopting a different window class, e.g.:

Exec=/opt/firefox_dev/firefox --class Firedev

2 Add the following desktop entry:


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