During the wee hours of the morning, David Faure posted a new mime applications specification which will allow to setup per-desktop default applications, for example, watching films in GNOME Videos in GNOME, but DragonPlayer in KDE. Up until now, this was implemented differently in at least KDE and GNOME, even to the point that GTK+ applications would use the GNOME default when running on a KDE desktop, and vice-versa.
This is made possible using XDG_CURRENT_DESKTOP as implemented in gdm by Lars. This environment variable will also allow implementing a more flexible OnlyShowIn and NotShowIn desktop entry fields (especially for desktops like Unity implemented on top of GNOME, or GNOME Classic implemented on top of GNOME) and desktop-specific GSettings/dconf configurations (again, very useful for GNOME Classic). The environment variable supports applying custom configuration in sequence (first GNOME Classic then GNOME in that example).
Today, Ryan and David discussed the desktop file cache, making it faster to access desktop file data without hitting scattered files. The partial implementation used a custom structure, but, after many kdbus discussions earlier in the week, Ryan came up with a format based on serialised GVariant, the same format as kdbus messages (but implementable without implementing a full GVariant parser).
We also spent quite a bit of time writing out requirements for a filesystem notification to support some of the unloved desktop use cases. Those use cases are currently not supported by either inotify and fanotify.
That will end our face-to-face meeting. Ryan and David led a Lunch'n'Learn in the SUSE offices to engineers excited about better application integration in the desktops irrespective of toolkits.
Many thanks to SUSE for the accommodation as well as hosting the meeting in sunny Nürnberg. Special thanks to Ludwig Nussel for the morning biscuits :)