The idea here is that we should process 'idle' events - like re-paint
after we have processed any OS messages - such as key/mouse input,
window re-size events etc.

The previous approach wasn't achieving this - it was processing a single
idle event each time around the main-loop iteration; urk.

Lubos implemented something -like- this, the vestiges of it need cleaning
up and removing in: 06d73142 but it was
disabled (most likely because it broke gtk in tdf#91727, which was itself
broken by using silly values for timeouts in the scheduler (now fixed))

Tested on Windows, gtk, kde4, unx-generic.

Change-Id: I7756bca874779c00f72b372cacb7745d0f189f66
Reviewed-on: https://gerrit.libreoffice.org/20158Reviewed-by: Michael Meeks <michael.meeks@collabora.com>
Tested-by: Michael Meeks <michael.meeks@collabora.com>