NB: My question is essentially identical to this, but it was recommended I open a new question as the given solution doesn't work.
Basically, I have Firefox Develop Edition installed. I managed to add the icon to the dock, and changed the icon to be correct. As such, I am 100% certain this is the correct .desktop file to be editing.
This is my firefox-developer.desktop file:
[Desktop Entry]
Version=1.0
Type=Application
Name=Firefox Developer Edition
Icon=/home/jhpratt/.local/share/umake/web/firefox-dev/browser/chrome/icons/default/default128.png
Exec=/home/jhpratt/.local/share/umake/web/firefox-dev/firefox %u
Comment=Firefox Aurora with Developer tools
Categories=Development;IDE;
Terminal=false
StartupWMClass=Firefox Developer Edition
The final line of this is what the recommended solution in the post above is. Running xprop WM_CLASS and clicking on the Firefox window returns WM_CLASS(STRING) = "Navigator", "Firefox Developer Edition". I have tried setting StartupWMClass to Navigator, Firefox Developer Edition, and Navigator, Firefox Developer Edition, none of which have worked. I restarted my session in between.
Update: It does not work in a Wayland session, but works as expected in Xorg.
