2008-10-21  Michael Natterer  <mitch@imendio.com>

	* gdk/gdkdraw.c
	* gdk/gdkimage.c
	* gdk/gdkscreen.c
	* gdk/gdkwindow.c: replace assertions for obj != NULL by
	GDK_IS_OBJ(), remove redundant != NULL checks when there is
	already a type check, add some g_return_if_fail() that were
	missing entirely, fix some broken indentation and spacing.


svn path=/trunk/; revision=21695