[gtk+] win32: destroy clipboard notification window on dispose

[Ignacio Casal Quinteiro <icq src gnome org>]

commit 1f5f3ca41bd2419e1aee3f210f683541a8a3f56f
Author: Ignacio Casal Quinteiro <icq gnome org>
Date:   Thu Nov 12 16:42:51 2015 +0100

    win32: destroy clipboard notification window on dispose
    
    The clipboard uses a hidden window to get some specific events.
    The window was created but never destroyed on dispose.

 gdk/win32/gdkdisplay-win32.c |   48 +++++++++++++++++++++++------------------
 gdk/win32/gdkdisplay-win32.h |    1 +
 2 files changed, 28 insertions(+), 21 deletions(-)
---
diff --git a/gdk/win32/gdkdisplay-win32.c b/gdk/win32/gdkdisplay-win32.c
index c819efc..7b1fbd8 100644
--- a/gdk/win32/gdkdisplay-win32.c
+++ b/gdk/win32/gdkdisplay-win32.c
@@ -570,30 +570,32 @@ _clipboard_window_procedure (HWND   hwnd,
 /*
  * Creates a hidden window and adds it to the clipboard chain
  */
-static HWND
-_gdk_win32_register_clipboard_notification (void)
+static gboolean
+register_clipboard_notification (GdkDisplay *display)
 {
+  GdkWin32Display *display_win32 = GDK_WIN32_DISPLAY (display);
   WNDCLASS wclass = { 0, };
-  HWND     hwnd;
-  ATOM     klass;
+  HWND hwnd;
+  ATOM klass;
 
   wclass.lpszClassName = "GdkClipboardNotification";
-  wclass.lpfnWndProc   = _clipboard_window_procedure;
-  wclass.hInstance     = _gdk_app_hmodule;
+  wclass.lpfnWndProc = _clipboard_window_procedure;
+  wclass.hInstance = _gdk_app_hmodule;
 
   klass = RegisterClass (&wclass);
   if (!klass)
-    return NULL;
+    return FALSE;
+
+  display_win32->clipboard_hwnd = CreateWindow (MAKEINTRESOURCE (klass),
+                                                NULL, WS_POPUP,
+                                                0, 0, 0, 0, NULL, NULL,
+                                                _gdk_app_hmodule, NULL);
 
-  hwnd = CreateWindow (MAKEINTRESOURCE (klass),
-                       NULL, WS_POPUP,
-                       0, 0, 0, 0, NULL, NULL,
-                       _gdk_app_hmodule, NULL);
-  if (!hwnd)
+  if (display_win32->clipboard_hwnd == NULL)
     goto failed;
 
   SetLastError (0);
-  _hwnd_next_viewer = SetClipboardViewer (hwnd);
+  _hwnd_next_viewer = SetClipboardViewer (display_win32->clipboard_hwnd);
 
   if (_hwnd_next_viewer == NULL && GetLastError() != 0)
     goto failed;
@@ -603,20 +605,20 @@ _gdk_win32_register_clipboard_notification (void)
   /* if (AddClipboardFormatListener (hwnd) == FALSE) */
   /*   goto failed; */
 
-  return hwnd;
+  return TRUE;
 
 failed:
   g_critical ("Failed to install clipboard viewer");
   UnregisterClass (MAKEINTRESOURCE (klass), _gdk_app_hmodule);
-  return NULL;
+  return FALSE;
 }
 
 static gboolean
 gdk_win32_display_request_selection_notification (GdkDisplay *display,
-                                                 GdkAtom     selection)
+                                                  GdkAtom     selection)
 
 {
-  static HWND hwndViewer = NULL;
+  GdkWin32Display *display_win32 = GDK_WIN32_DISPLAY (display);
   gboolean ret = FALSE;
 
   GDK_NOTE (DND,
@@ -626,12 +628,14 @@ gdk_win32_display_request_selection_notification (GdkDisplay *display,
   if (selection == GDK_SELECTION_CLIPBOARD ||
       selection == GDK_SELECTION_PRIMARY)
     {
-      if (!hwndViewer)
+      if (display_win32->clipboard_hwnd == NULL)
         {
-          hwndViewer = _gdk_win32_register_clipboard_notification ();
-          GDK_NOTE (DND, g_print (" registered"));
+          if (register_clipboard_notification (display))
+            GDK_NOTE (DND, g_print (" registered"));
+          else
+            GDK_NOTE (DND, g_print (" failed to register"));
         }
-      ret = (hwndViewer != NULL);
+      ret = (display_win32->clipboard_hwnd != NULL);
     }
   else
     {
@@ -711,6 +715,8 @@ gdk_win32_display_dispose (GObject *object)
   GdkWin32Display *display_win32 = GDK_WIN32_DISPLAY (object);
 
   g_clear_pointer (&display_win32->hwnd, (GDestroyNotify)DestroyWindow);
+  g_clear_pointer (&display_win32->clipboard_hwnd, (GDestroyNotify)DestroyWindow);
+  _hwnd_next_viewer = NULL;
 
   G_OBJECT_CLASS (gdk_win32_display_parent_class)->dispose (object);
 }
diff --git a/gdk/win32/gdkdisplay-win32.h b/gdk/win32/gdkdisplay-win32.h
index 8cb0861..250c13b 100644
--- a/gdk/win32/gdkdisplay-win32.h
+++ b/gdk/win32/gdkdisplay-win32.h
@@ -32,6 +32,7 @@ struct _GdkWin32Display
   GHashTable *cursor_cache;
 
   HWND hwnd;
+  HWND clipboard_hwnd;
 
   /* WGL/OpenGL Items */
   guint have_wgl : 1;