This is very simple documentation for the 'override' GSettings key for
gnome-setting-daemon's xsettings plugin.

The override is given as a dictionary of overrides to be applied on top
of the usual values that are exported to the X server as XSETTINGS.  The
intent of this is to allow users to override values of programmatically
determined settings (such as 'Gtk/ShellShowsAppMenu') and to allow
developers to introduce new XSETTINGS for testing (without having to kill the
gnome-settings-daemon running in the session and run their own patched
version).

The type of the overrides is 'a{sv}'.

The key gives the full XSETTINGS setting name to override (for example,
'Gtk/ShellShowsAppMenu').  The value is one of the following:

 - a string ('s') for the case of a string XSETTING

 - an int32 ('i') for the case of an integer XSETTING

 - a 4-tuple of uint16s ('(qqqq)') for the case of a color XSETTING

Dictionary items with a value that is not one of the above types will be
ignored.  Specifically note that XSETTINGS does not have a concept of
booleans -- you must use an integer that is either 0 or 1.

An example setting for this key (as expressed in GVariant text format)
might be:

 { 'Gtk/ShellShowsAppMenu': < 0 >, 'Xft/DPI': < 98304 > }

Noting that variants must be specified in the usual way (wrapped in <>).

Note also that DPI in the above example is expressed in 1024ths of an
inch.