Comment 49 for bug 595265

[workaround]

I figured out what it is...

This gave me the clue
Trying to register gtype 'WnckWindowMoveResizeMask' as enum when in fact it is of type 'GFlags'

gwibber add facebook conflicts with Compiz.

I went to System... Look and Feel... Visual Effects...
chose none....
then close

then opened gwibber added facebook... add button shows up...

then went back and turned Compiz back on using
I went to System... Look and Feel... Visual Effects...
chose extra....

gwibber works just fine...

So just for adding Facebook you need to turn off Compiz for a minute.