Gnome extension says to change Meta.keybindings_set_custom_handler. What is this, and how do I change it

Question

After Ubuntu switched to Gnome, I installed the workspace-grid Gnome extension to have a grid of workspaces like in Unity. While I can switch left and right using ctrl+alt+left/right arrow key, moving up and down is more tricky. I need to use function+super+up/down key. It's jarring having to switch keys for the same action. Also, in some applications like Chrome, pressing function+super+up/down key scrolls down instead of changing workspace. I would like to change the up/down shortcut to ctrl+alt+up/down arrow key.

Looking at the github repo for the extension, it says:

Workspaces can be changed by the user by a number of ways, and the ways this extension overrides are:

• keybindings (Main.wm.setKeybindingHandler (GNOME 3.2), Meta.keybindings_set_custom_handler (GNOME 3.4))

So what is Meta.keybindings_set_custom_handler and how do I go about setting it?

Answer 1

Meta.keybindings_set_custom_handler refers to the gnome3 sourcecode - this is not a "setting" in the normal sense.

It is a function in the gnome-shell sourcecode in javascript, see here

  setCustomKeybindingHandler: function(name, modes, handler) {
        if (Meta.keybindings_set_custom_handler(name, handler))
            this.allowKeybinding(name, modes);
    },

or in use, at this custom extension

function enable() {
    Meta.keybindings_set_custom_handler('switch-group', _doSwitchDesktop);
    Meta.keybindings_set_custom_handler('switch-group-backward', _doSwitchDesktop);
}

function disable() {
    Meta.keybindings_set_custom_handler('switch-group', Lang.bind(Main.wm, Main.wm._startAppSwitcher));
    Meta.keybindings_set_custom_handler('switch-group-backward', Lang.bind(Main.wm, Main.wm._startAppSwitcher));
}

If you write your own extension or rewrite an existing one, you can "set" it - if you will.