gnome calendar problems

Problem: "gnome-control-center" empty

Solution:

$ env XDG_CURRENT_DESKTOP=GNOME gnome-control-center

Problem: gnome calendar google shared calendars missing

Solution: Enable sync in https://calendar.google.com/calendar/syncselect

Problem: Nextcloud/ownCloud account setup window misses buttons

Solution:

$ export GTK_CSD="1"
$ env XDG_CURRENT_DESKTOP=GNOME gnome-control-center

Bug: https://github.com/PCMan/gtk3-nocsd/issues/49