It's not just a GNOME thing, but it might not be that cross-platform. On Linux, there's a firefox.desktop file that describes the application to your DE/launche

It's not just a GNOME thing, but it might not be that cross-platform. On Linux, there's a firefox.desktop file that describes the application to your DE/launcher, and it looks like this on my box: [Desktop Entry] Actions=new-private-window;new-window;profile-manager-window Categories=Network;WebBrowser Exec=firefox --name firefox %U ---snip--- [Desktop Action profile-manager-window] Exec=firefox --ProfileManager Name=Profile Manager So that'll work on anything that uses https://specifications.freedesktop.org/desktop-entry-spec/desktop-entry-spec-latest.html https://specifications.freedesktop.org/desktop-entry-spec/de... and there could be parallel features for Windows/Mac, but there also might not be or Firefox might not implement them.