Ok, I finally fixed the issue. Unfortunately it was not just the distinction between "flip physics" and "flip image" (which is history now, btw.). Splitters have a very weird relationship between graphics and physics. Behold the ingenuity:
- When read from the level file, the info whether the starting direction is flipped or not is stored in the FlipPhysics flag.
- Then the images for the splitter are determined and the flipped images are loaded if the FlipPhysics flag is set.
- When finally creating the actual gadget, the starting frame (of the two sprites a splitter may have) is chosen depending on the FlipPhysics flag.
- The actual game physics are then tied completely to the frame index and each passing lemming swaps the frame index. This does not care at all whether the splitter is actually flipped or not.