Reuse the existing infrastructure in GtkActionMuxer for propagation of
accelerator information: in particular, what accel label ought to appear
on menu items for a particular action and target.
This is a good idea because we want accels to travel along with the
actions that they're tied to and reusing GtkActionMuxer will allow us to
do that without creating another hierarchy of a different class for the
sole purpose of filling in accel labels on menu items.
Doing it this ways also allows those who copy/paste GtkActionMuxer to
insert the accels for themselves.
Add a new method on the GtkActionObserver interface to report changes.
This patch introduces a new concept: "action and target" notation for
actions. This format looks like so:
"'target'|app.action"
or for non-targeted actions:
"|app.action"
and it is used over a number of possible alternative formats for some
good reasons:
- it's very easy to get a nul-terminated action name out of this format
when we need it, by using strrchr('|') + 1
- we can also get the target out of it using g_variant_parse() because
this function takes a pointer to a 'limit' character that is not
parsed past: we use the '|' for this
- it's extremely easy to hash on this format (just use a normal string
hash) vs. attempting to hash on a string plus a GVariant
A close contender was to use detailed action strings here, but these are
not used for two reasons:
- it's not possible to easily get the action name or target out of the
strings without more work than the "action and target" format
requires
- we still intend to use detailed action strings on API (since they are
a lot nicer to look at) but detailed action strings can be given in
non-canonical forms (eg: 'foo::bar' and 'foo("bar")' are equivalent)
so we'd have to go through a normalisation step anyway. Since we're
doing that already, we may as well convert to a more convenient
internal format.
This new "action and target" format is going to start appearing in a lot
more places as action descriptions are introduced.
I suspect that nobody is using '|' in their action names, but in case I
am proven wrong, we can always switch to using something more exotic as
a separator character (such as '\x01' or '\xff' or the like).
Rename our internal GActionMuxer, GActionObserver and GActionObservable
classes and interfaces to have names in our own namespace.
These classes were originally intended for GIO but turned out to be too
special-purpose to be useful there, so we never made them public API but
have just been copying them around (without bothering to properly rename
them). Now that other people will be copying them out of Gtk, it's even
more important to prevent this namespace abuse from spreading further.
