Move GdkWindowWindowClass to private headers

This enum is no longer used in public api.

gdk/gdkinternals.h

@@ -156,6 +156,13 @@ struct _GdkEventPrivate
 
 typedef struct _GdkWindowPaint GdkWindowPaint;
 
+typedef enum
+{
+  GDK_INPUT_OUTPUT,
+  GDK_INPUT_ONLY
+} GdkWindowWindowClass;
+
+
 struct _GdkWindowAttr
 {
   gint event_mask;

gdk/gdkwindow.h

@@ -39,23 +39,6 @@ G_BEGIN_DECLS
 
 typedef struct _GdkGeometry          GdkGeometry;
 
-/**
- * GdkWindowWindowClass:
- * @GDK_INPUT_OUTPUT: window for graphics and events
- * @GDK_INPUT_ONLY: window for events only
- *
- * @GDK_INPUT_OUTPUT windows are the standard kind of window you might expect.
- * Such windows receive events and are also displayed on screen.
- * @GDK_INPUT_ONLY windows are invisible; they are usually placed above other
- * windows in order to trap or filter the events. You can’t draw on
- * @GDK_INPUT_ONLY windows.
- */
-typedef enum
-{
-  GDK_INPUT_OUTPUT, /*< nick=input-output >*/
-  GDK_INPUT_ONLY    /*< nick=input-only >*/
-} GdkWindowWindowClass;
-
 /**
  * GdkWindowType:
  * @GDK_WINDOW_ROOT: root window; this window has no parent, covers the entire