Rick and Morty Icon Overlay for Gtk

• 48x48 is what is used in the Ubuntu dock.
• 256x256 is what is used in the Ubuntu applications menu.

You can find the name of applications at "/usr/share/applications" and "~/.local/share/applications". Print the file with cat and look at the field Icon that's the file name you should use for your PNG.

I'm not sure what you can do about programs that are using a PNG file path in the Icon field.

References

• https://specifications.freedesktop.org/icon-theme-spec/icon-theme-spec-latest.html
• https://www.reddit.com/r/gnome/comments/yxm32e/comment/iwphtm1/
• https://www.reddit.com/r/gnome/comments/yzwsji/how_to_change_the_default_icon_for_folders_in/
• https://help.gnome.org/admin//system-admin-guide/2.32/themes-11.html.en
• https://github.com/surajmandalcell/Gtk-Theming-Guide