GNOME Flashback 3.36 will have better multi-monitor support. Currently due to limitation in existing Extended Window Manager Hints specification it is impossible to have panels between two monitors. The problem is with existing _NET_WM_STRUT, _NET_WM_STRUT_PARTIAL and _NET_WORKAREA properties.
Today I released GNOME Panel 3.35.1. This is small release that makes new libgnome-panel library public, changes default layout location and fixes crashes in clock module when using wheather locations that does not have timezone information.
For very long time I am working on new libgnome-panel library. It is still private library, but at some point it will become public replacing old libpanel-applet library. My own requirement to make it public is that all internal objects are ported to new library.
After GNOME Panel 3.30 release I have finished converting menu objects to menu module. To keep existing functionality I had to introduce new functionality that will be available also to 3rd party applet developers once library will be public.