[gtk+] Win32: Ensure native back-end for windows where the user requests their handle

[Alexander Larsson <alexl src gnome org>]

commit f9d8f9758bfe1417416e0b2bbea955f1cee75674
Author: Peter Clifton <pcjc2 cam ac uk>
Date:   Fri Sep 9 15:17:29 2011 +0100

    Win32: Ensure native back-end for windows where the user requests their handle
    
    https://bugzilla.gnome.org/show_bug.cgi?id=658841

 gdk/win32/gdkwindow-win32.c |   10 ++++++++++
 1 files changed, 10 insertions(+), 0 deletions(-)
---
diff --git a/gdk/win32/gdkwindow-win32.c b/gdk/win32/gdkwindow-win32.c
index 25851e0..a8f1cbc 100644
--- a/gdk/win32/gdkwindow-win32.c
+++ b/gdk/win32/gdkwindow-win32.c
@@ -3409,5 +3409,15 @@ gdk_window_impl_win32_class_init (GdkWindowImplWin32Class *klass)
 HGDIOBJ
 gdk_win32_window_get_handle (GdkWindow *window)
 {
+  /* Try to ensure the window has a native window */
+  if (!_gdk_window_has_impl (window))
+    gdk_window_ensure_native (window);
+
+  if (!GDK_WINDOW_IS_WIN32 (window))
+    {
+      g_warning (G_STRLOC " window is not a native Win32 window");
+      return NULL;
+    }
+
   return GDK_WINDOW_HWND (window);
 }