merge gtk3 change from metacity
gtk3: fix warnings
move meta_gtk_style_get_light_color to mate-desktop
gtk3: fix warnings
merge metacity(gtk3) changes

merge metacity(gtk3) changes
fix warnings
clean up unused variables
replace UNUSED_VARIABLE by G_GNUC_UNUSED
Merge branch 'meta'

Conflicts:
	src/ui/tile-preview.c
Merge branch 'metacity'