riched20: Adjust event mask when sending EN_CHANGE notification.

dlls/riched20/paint.c

@@ -120,7 +120,9 @@ void ME_UpdateRepaint(ME_TextEditor *editor)
   /* send EN_CHANGE if the event mask asks for it */
   if(editor->nEventMask & ENM_CHANGE)
   {
+    editor->nEventMask &= ~ENM_CHANGE;
     ME_SendOldNotify(editor, EN_CHANGE);
+    editor->nEventMask |= ENM_CHANGE;
   }
   ME_Repaint(editor);
   ME_SendSelChange(editor);

dlls/riched20/tests/editor.c

@@ -2023,10 +2023,8 @@ static void test_eventMask(void)
     ok(ret == TRUE, "failed to set text\n");
     /* richedit should mask off ENM_CHANGE when it sends an EN_CHANGE
        notification in response to WM_SETTEXT */
-todo_wine {
     ok(queriedEventMask == (eventMask & ~ENM_CHANGE),
             "wrong event mask (0x%x) during WM_COMMAND\n", queriedEventMask);
-}
 
 }