gtk3 and LibreOffice

Couple of changes to the gtk3 support in LibreOffice master recently.

Theming stuff

The gtk3 support in master LibreOffice is now updated to support the relatively recent changes in gtk 3.19's style mechanism.

With mclasen's help I've added simple demos to the foreign-drawing demo of gtk-demo for the different elements that we render via those rendering apis. So what we attempt to do in LibreOffice is basically documented in gtk-demo now. So from 3.20 onwards if there are styling flaws in LibreOffice, then gtk-demo can be checked if it has the same problem or not.

Drag and Drop

Drag and Drop is now implemented in the gtk3 backend. DnD here includes moving blocks of cells around a calc spreadsheet using the mouse alone.

Wayland gstreamer video playback

If the gtksink gstreamer element is present (e.g. gstreamer >= 1.7.1 as in Fedora 24) then the gtksink gtk widget integration will be used to play video. Which means support for video playback in LibreOffice under wayland.