I use this guide: https://wiki.xfce.org/howto/add_simple_shortcut_to_folder to add shortcut for Mozilla Firefox to panel 2. On step 8 -> Icon -> Select icon from: -> All icons the Firefox icons are missing. Manually select from Image Files -> "/usr/lib/firefox/browser/chrome/icons/default/" Could those icons be available on All icons group?
Which distribution is that? How did you install Firefox?
It's ubuntu 20.04 LTS. The icon should be listed into "Application Icons" not "All Icons" by the way.
Created attachment 9782 Apps versions
/usr/share/icons/hicolor/128x128/apps/firefox.png /usr/share/icons/hicolor/16x16/apps/firefox.png /usr/share/icons/hicolor/32x32/apps/firefox.png /usr/share/icons/hicolor/48x48/apps/firefox.png /usr/share/icons/hicolor/64x64/apps/firefox.png Are those icon files symbolic links? If yes -> Bug 10126.
find /usr/share/icons/hicolor/ | grep -i firefox | xargs file /usr/share/icons/hicolor/32x32/apps/firefox.png: symbolic link to ../../../../../lib/firefox/browser/chrome/icons/default/default32.png /usr/share/icons/hicolor/16x16/apps/firefox.png: symbolic link to ../../../../../lib/firefox/browser/chrome/icons/default/default16.png /usr/share/icons/hicolor/64x64/apps/firefox.png: symbolic link to ../../../../../lib/firefox/browser/chrome/icons/default/default64.png /usr/share/icons/hicolor/symbolic/apps/firefox-symbolic.svg: SVG Scalable Vector Graphics image /usr/share/icons/hicolor/48x48/apps/firefox.png: symbolic link to ../../../../../lib/firefox/browser/chrome/icons/default/default48.png /usr/share/icons/hicolor/128x128/apps/firefox.png: symbolic link to ../../../../../lib/firefox/browser/chrome/icons/default/default128.png
*** This bug has been marked as a duplicate of bug 10126 ***