* gdesktop-prefs.[ch]: New files that handle the desktop
preferences page. Now we have a nice way to configure the
position of desktop icons.
* gprefs.c (create_prop_box): Use desktop_prefs_new() to create
the desktop preferences page.
(apply_page_changes): Do not update the desktop here.
(apply_callback): Take the desktop page into account.
* gdesktop.c (desktop_use_shaped_text): Renamed from
desktop_use_transparent_text.
* Makefile.in: Added gdesktop-prefs.[ch] to the list of sources.