A simple Evolution run and move between all views means creation of
more than 100 GSettings objects, with only a bit more than 10 schemas.
Reusing the objects should have a positive impact on a performance too.
EShellSettings predates GSettings and is no longer necessary.
GSettings allows binding GObject properties to GSettings keys,
with optional mapping functions. That fulfills the purpose of
EShellSettings.
The EModule, EExtensible and EExtension classes as well as the
e_type_traverse() function have been moved to Evolution-Data-Server's
libebackend library to replace e-data-server-module.c.
Now Evolution-Data-Server modules use the same framework as Evolution.
If we're using GTK+ 2.21.8 (where gtk_dialog_set_has_separator() is
deprecated but the property is still present and defaults to TRUE), we
still need to set the property to FALSE. So instead use g_object_set()
up through GTK+ 2.90.6, after which the property itself is gone.
Unfortunately the default value for this property is TRUE (bzzt, WRONG!)
so we can't just remove the function outright until we require GTK+ 2.22.
It was deprecated in GTK+ 2.21.8.
