Documentation for gnome shell extension development?

The reason I'm not happy with the demo code and tutorials is that they introduce a bunch of random imports and never explain what they are or how to use them. I'm constructing my own answer that others can add to, so that people can actually know what functions they can call, what they can import, etc.

There is generated documentation for Gnome Shell, but it is somewhat incomplete — I couldn't find most of the things I saw in various tutorials, examples and published extensions.

The only really reliable documentation is the Gnome Shell source itself. There simply isn't any other up-to-date or complete way to know what's available.

These two starting points are particularly good:

• The Gnome Shell C source
• The Gnome Shell JS source

The C source shows that there is an important object called global that doesn't need to be imported, and provides access to things like the window manager (including keybindings), the session information, the screens available and other such things. Here's the source:

• The shell-global.c source itself
• The part of the source where the available properties are added
• The part of the source that shows you the types of the underlying objects

I wanted to know how to use the global.display object, and for now the best documentation is that provided by Alan Knowles.

Other things can be imported via the GObject introspection bindings, for example:

• The Clutter UI library (imports.gi.Clutter)
• GLib itself (imports.gi.GLib)
• The Shell Toolkit (imports.gi.St)

In general, you can look through the reference documentation for the various Gnome components to find other imports.

A note on the looking glass: There are some quirks about using these imports in the looking glass though — I wasted a lot of time just trying to test things out on the fly. For example:

const Clutter = imports.gi.Clutter;

...won't work, because Clutter already exists. But then:

const MyClutter = imports.gi.Clutter;

...also won't work; MyClutter is undefined and can't be used. You have to do:

MyClutter = imports.gi.Clutter;

Of course, in this case Clutter already exists, so it's not really necessary. But since it's not documented what is and isn't already in the looking glass namespace, if you try to import something and have these problems, keep it in mind.

Remaining questions:

• What is Mainloop? This is imported in main.js and appears to have functions related to the GLib main loop. Is there documentation for this?
• What is imports.misc? It seems to have some really useful things in there, like ExtensionUtils — what's that?
• How do you use DBus? What about introspection?

Documentation is lagging a bit, one potential source of information is Musings of an OS plumber, e.g. this post on updating GNOME Shell extensions to work with version 3.2

Depending on what information you want, you might try the gnome mailing list.

This Step by step tutorial to create extensions for gnome 3.4 may help: https://live.gnome.org/GnomeShell/Extensions/StepByStepTutorial