Setting window properties (always on top, ...) in gnome shell extension

[Amy C <mathematical coffee gmail com>]

Hi all,

As part of teaching myself how to make gnome shell extensions, I
decided to just add an item to the menu of the panel's title bar that
allows the user to select options like always on top/always on this
workspace.

I notice in the mutter API there is a meta_window_set_above in
window.c but this doesn't seem to be exposed to the JS interface.
Through a bit of trial and error I also seem to be able to call
window.set_property('above',true) but this function appears to do
nothing (there is a 'title' property I tested on and using
set_property on this also seems to do nothing).

I could simulate (e.g.) always in this workspace by listening to a
workspace changed event and moving the relevant window, but this would
not be a "true" implementation in that the window manager still thinks
that window.is_on_all_workspaces is false (as I don't seem to be able
to set it).

So, does anyone know:
- an alternate way to set these window properties (properly, as in the
window manager knows about it) in a gnome shell extension?
- how to tell whether a likely function in a c file (e.g.
meta_window_set_above) has been exported to the JS interface?
- how to expose a method from the C interface to the JS interface?

cheers!