I have an application (an AppImage) that I start with ./KDevelop.AppImage &
When it starts there is an icon in my favorites bar (Ubuntu Dock), but when I right click on that there is no option to "add to favorites".
How can I add this to favorites?
If you are in Ubuntu 18.04: When you run the appimage it asks you if it should integrate it into the system. If you choose yes then you can search it on the shell and right-clicking on it (before running) will give you the option to add to Favorites.
Here is an example:
In the first run of APPImage,you may miss the "integrate and run" button and choose the "run" button like
If you don't mind install again, I'm sure you know what to do. But if you can't, AppImageLauncher may help. https://github.com/TheAssassin/AppImageLauncher for details.