raw: Allow Nothing openPtr with flags (#213)

Author: dpwiz

src/DearImGui/Raw.hs

@@ -569,6 +569,8 @@ styleColorsClassic = liftIO do
 begin :: (MonadIO m) => CString -> Maybe (Ptr CBool) -> Maybe (ImGuiWindowFlags) -> m Bool
 begin namePtr (Just openPtr) (Just flags) = liftIO do
   (0 /=) <$> [C.exp| bool { Begin($(char* namePtr), $(bool* openPtr), $(ImGuiWindowFlags flags)) } |]
+begin namePtr Nothing (Just flags) = liftIO do
+  (0 /=) <$> [C.exp| bool { Begin($(char* namePtr), NULL, $(ImGuiWindowFlags flags)) } |]
 begin namePtr (Just openPtr) Nothing = liftIO do
   (0 /=) <$> [C.exp| bool { Begin($(char* namePtr), $(bool* openPtr)) } |]
 begin namePtr Nothing Nothing = liftIO do