diff --git a/gdk/gdkinternals.h b/gdk/gdkinternals.h
index e85491a099..17c914ce7a 100644
--- a/gdk/gdkinternals.h
+++ b/gdk/gdkinternals.h
@@ -225,9 +225,6 @@ void _gdk_windowing_event_data_copy (const GdkEvent *src,
                                      GdkEvent       *dst);
 void _gdk_windowing_event_data_free (GdkEvent       *event);
 
-void gdk_surface_set_state (GdkSurface      *surface,
-                            GdkSurfaceState  new_state);
-
 gboolean        _gdk_cairo_surface_extents       (cairo_surface_t *surface,
                                                   GdkRectangle    *extents);
 void            gdk_gl_texture_from_surface      (cairo_surface_t *surface,
diff --git a/gdk/gdksurfaceprivate.h b/gdk/gdksurfaceprivate.h
new file mode 100644
index 0000000000..664ad7e2e9
--- /dev/null
+++ b/gdk/gdksurfaceprivate.h
@@ -0,0 +1,123 @@
+/* GDK - The GIMP Drawing Kit
+ * Copyright (C) 2019 Red Hat, Inc.
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Uninstalled header defining types and functions internal to GDK */
+
+#ifndef __GDK_SURFACE_PRIVATE_H__
+#define __GDK_SURFACE_PRIVATE_H__
+
+#include <gdk-pixbuf/gdk-pixbuf.h>
+#include "gdksurfaceimpl.h"
+#include "gdkenumtypes.h"
+#include "gdksurface.h"
+
+G_BEGIN_DECLS
+
+struct _GdkSurface
+{
+  GObject parent_instance;
+
+  GdkDisplay *display;
+
+  GdkSurfaceImpl *impl; /* window-system-specific delegate object */
+
+  GdkSurface *transient_for;
+
+  gpointer widget;
+
+  gint x;
+  gint y;
+
+  guint8 surface_type;
+
+  guint8 resize_count;
+
+  GdkGLContext *gl_paint_context;
+
+  cairo_region_t *update_area;
+  guint update_freeze_count;
+  /* This is the update_area that was in effect when the current expose
+     started. It may be smaller than the expose area if we'e painting
+     more than we have to, but it represents the "true" damage. */
+  cairo_region_t *active_update_area;
+
+  GdkSurfaceState old_state;
+  GdkSurfaceState state;
+
+  guint8 alpha;
+  guint8 fullscreen_mode;
+
+  guint modal_hint : 1;
+
+  guint destroyed : 2;
+
+  guint accept_focus : 1;
+  guint focus_on_map : 1;
+  guint support_multidevice : 1;
+  guint viewable : 1; /* mapped and all parents mapped */
+  guint in_update : 1;
+  guint frame_clock_events_paused : 1;
+
+  /* The GdkSurface that has the impl, ref:ed if another surface.
+   * This ref is required to keep the wrapper of the impl surface alive
+   * for as long as any GdkSurface references the impl. */
+  GdkSurface *impl_surface;
+
+  guint update_and_descendants_freeze_count;
+
+  gint width, height;
+  gint shadow_top;
+  gint shadow_left;
+  gint shadow_right;
+  gint shadow_bottom;
+
+  GdkCursor *cursor;
+  GHashTable *device_cursor;
+
+  cairo_region_t *input_shape;
+
+  GList *devices_inside;
+
+  GdkFrameClock *frame_clock; /* NULL to use from parent or default */
+
+  GSList *draw_contexts;
+  GdkDrawContext *paint_context;
+
+  cairo_region_t *opaque_region;
+};
+
+struct _GdkSurfaceClass
+{
+  GObjectClass      parent_class;
+
+  /* Padding for future expansion */
+  void (*_gdk_reserved1) (void);
+  void (*_gdk_reserved2) (void);
+  void (*_gdk_reserved3) (void);
+  void (*_gdk_reserved4) (void);
+  void (*_gdk_reserved5) (void);
+  void (*_gdk_reserved6) (void);
+  void (*_gdk_reserved7) (void);
+  void (*_gdk_reserved8) (void);
+};
+
+void gdk_surface_set_state (GdkSurface      *surface,
+                            GdkSurfaceState  new_state);
+
+G_END_DECLS
+
+#endif /* __GDK_SURFACE_PRIVATE_H__ */