Cache the display name. There is only one GdkDisplay on Win32, and

Cache the display name. There is only one GdkDisplay on Win32, and

2005-09-09  Tor Lillqvist  <tml@novell.com>

	* gdk/win32/gdkdisplay-win32.c (gdk_display_get_name): Cache the
	display name. There is only one GdkDisplay on Win32, and
	constructing the display name isn't entirely trivial, so cacheing
	is probably worth it. For instance GIMP calls this function a lot.
	(gdk_display_open): Call gdk_display_get_name() to prime the
	cached name.
	(gdk_display_get_n_screens, gdk_display_get_screen,
	gdk_display_get_default_screen): Verify parameter correctness like
	the X11 backend does.

	* gdk/win32/gdkscreen-win32.c (gdk_screen_make_display_name):
	Return a freshly allocated string, as the API specifies. Fixes a
	heap corruption problem that caused random errors and crashes in
	GIMP, for instance.