All code interacting with Objective-C objects should now use Automated
Reference Counting rather than manual memory management or Garbage
Collection. Because ARC prohibits C-structs from containing
references to Objective-C objects, all such fields are now typed
'gpointer'. Setting and gettings Objective-C fields on such a
struct now uses explicit __bridge_* calls to tell ARC about
object lifetimes.
https://bugzilla.gnome.org/show_bug.cgi?id=777847
Using NSApp directly seems to confuse something, as the compiler
was expecting an id<NSFileManagerDelegate>. Switched to using
[NSApplication sharedApplication], and specified the delegate
protocol on the window class as well.
Similar to https://bugzilla.gnome.org/show_bug.cgi?id=738740
Until gcc and GNUStep properly support Objective-C blocks and other
"new" features of Objective-C we can't properly support them without
making the code much more ugly.
https://bugzilla.gnome.org/show_bug.cgi?id=739152
