gnome-shell magnifier

Hello all,

I've just started using gnome 3, specifically 3.8.1, and I am a
magnifier user.  I have a few questions:

1.  Is there some way to adjust the granularity of the keyboard shortcut
for the magnification?  200%, 300%, etc is too coarse.  I did see that I
could increment by 25% in the accessibility settings dialog but not with
the shortcut.  I do realize I could set the shortcut for something and
then use the on/off toggle to switch between but I don't always use the
same level.  If this is addressed somewhere else please point me in that
direction.

2.  Is there some way to create a keyboard shortcut for reverse video?
I don't need it all the time and going to the settings dialog every time
is a bit of a PITA.

Thanks in advance for any assistance.  Again, if this is documented
somewhere that I've not been able to find via google, please point me in
that direction.

Best regards,
rdc

-- 
Robert D. Crawford                                     [email protected]