Bug 668663 - OFNHookProc callback in the file picker code should return a UINT_PTR. r=neil

widget/src/windows/nsFilePicker.cpp

@@ -99,8 +99,8 @@ int CALLBACK BrowseCallbackProc(HWND hwnd, UINT uMsg, LPARAM lParam, LPARAM lpDa
 
 // Callback hook which will dynamically allocate a buffer large
 // enough for the file picker dialog.
-static unsigned int CALLBACK FilePickerHook(HWND hwnd, UINT msg,
-                                            WPARAM wParam, LPARAM lParam)
+static UINT_PTR CALLBACK FilePickerHook(HWND hwnd, UINT msg,
+                                        WPARAM wParam, LPARAM lParam)
 {
   switch (msg) {
     case WM_INITDIALOG: