Super+O unavailable for shortcuts; no bindings

As recommended on Ubuntu-GNOME mailing list, please see below description of the issue:

It is not possible to assign the Super+O shortcut to a script and it seems a Gnome process intercepts it. I've arrived to this conclusion because:

- Using xev within a terminal in the graphical session shows
KeymapNotify event and doesn't show keycode.
- Using xev within xterm launched from a console session shows the
expected keycodes (for super key & o key)
- Booting using Ubuntu GNOME live CD has the same issues (shortcut
Super+O cannot be used)
- Booting using Ubuntu live CD doesn't have the issue (xev shows the
expected keycodes & I can attribute Super+O shortcut to stuff, I tested
with launching the help browser)

I've gone through all I could think off (de-activating all shell extensions, extracting all shortcuts with a script given on askubuntu
that's meant to be used for backing up shortcuts and manually going through dconf-editor at all places where shortcuts are) without finding what could use this shortcut. Maybe the answer is quite easy and I'm missing something.

The only reference I've found is the following is on a Fedora website where it says that it's to lock screen orientation (which ironically is what I would like to do but using scripts since the screen doesn't rotate automatically) but there's no reference to where the bindings are defined.

Perhaps something a bit similar but shift+LaunchA shortcut works while only LaunchA doesn't and I also cannot find LaunchA registered anywhere.

Information: Ubuntu GOME 15.04 running Gnome 3.14 but another user reported the same with Wily and Gnome 3.16.

Regards,

Thomas