[REVIEW 3-5] idle-callbacks in writer don't end early, so your responsiveness sucks rocks

This one has nearly killed me trying to track down because its *so*
variable, but "unusably slow with large documents"
https://bugs.freedesktop.org/show_bug.cgi?id=48011

I believe is fixed by
http://cgit.freedesktop.org/libreoffice/core/commit/?id=658954e8b50fc264428402dc5a95b0d6f690d191
or at least that's a lot of the problem as far as I can tell, takes away
a 6 second lag I can reproduce on an i7

i.e. the idle-callbacks in writer are trying to stop if there's any
unprocessed keyboard, mouse, paint, etc events and the new AnyInput impl
doesn't quite cut it.

How about the above ?, return to using the old-school traditional one
for gtk2. And maybe the proposed gtk3 one is sufficient for gtk3,
definitely the alternative impl *seems* ok for gtk2 is I enable it
locally experimentally.

C.