Fix data type casting when setting up menus on Windows.

 src/w32menu.c (add_menu_item): Cast to UINT_PTR when assigning
 info.dwItemData.  Fixes crashes on 64-bit Windows.  Suggested by
 Fabrice Popineau <fabrice.popineau@supelec.fr>.

src/ChangeLog

+2012-07-21  Eli Zaretskii  <eliz@gnu.org>
+
+	* w32menu.c (add_menu_item): Cast to UINT_PTR when assigning
+	info.dwItemData.  Fixes crashes on 64-bit Windows.  Suggested by
+	Fabrice Popineau <fabrice.popineau@supelec.fr>.
+
 2012-07-21  Jan Djärv  <jan.h.d@swipnet.se>
 	* nsterm.m (accessibilityAttributeValue): New function. (Bug#11134).

src/w32menu.c

@@ -1533,7 +1533,14 @@ add_menu_item (HMENU menu, widget_value *wv, HMENU item)
 	     until it is ready to be displayed, since GC can happen while
 	     menus are active.  */
 	  if (!NILP (wv->help))
-	    info.dwItemData = (DWORD) XLI (wv->help);
+	    {
+	      /* As of Jul-2012, w32api headers say that dwItemData
+		 has DWORD type, but that's a bug: it should actually
+		 be UINT_PTR, which is correct for 32-bit and 64-bit
+		 Windows alike.  MSVC headers get it right; hopefully,
+		 MinGW headers will, too.  */
+	      info.dwItemData = (UINT_PTR) XLI (wv->help);
+	    }
 	  if (wv->button_type == BUTTON_TYPE_RADIO)
 	    {
 	      /* CheckMenuRadioItem allows us to differentiate TOGGLE and