If you turn off fringe drawing in layer six, you can copy individual pieces of fringe from place to place with the copy tool. It's not a perfect solution, but it would look slightly better. The problem is that there isn't a single tile with two different brick colors in it. Normally, the tile fringe gets put in layers one through three, so they can lie on top of each other, but layer six has no way of doing that.

Yeah. In some future version of Midnight Mansion, I hope there can be a layer 7, so we can hide secrets a little more seamlessly.

@Frost:

I have to admit, I don't really understand what causes your concern (in your picture above) ??!

The right layer-6 block looks just like the left one....except that some half-bricks are green (which looks strange even in layer-4) !

Or am I missing something ??    

You know, one solution I've found is to put the fake wall in the background instead of the foreground. It takes a little bit more work, because the game won't add the 3d fringe automatically, but it hides the secrets even more effectively than layer 6 will. And then you can add proper fringe by copying stuff from layers 1 through 3 and pasting it in layers 4 and 5.

Not really. I had to experiment with it a lot before I could do anything useful, and I do it mostly by instinct now. But I can give you some tips.

The 3D fringe for blocks in layer 4 is placed into layers 1 through 3. Those fringe tiles are just like regular tiles, except that you can't access them directly from the tile scroll bar. I don't know exactly how the editor decides which layer to put the fringe into, so when I need a piece of fringe, I make a shape in layer 4 that will produce the right kind of fringe, and then I switch to layer 1. I select the piece of fringe I want, copy it, and paste it to see what I've got. With luck, I've got some 3d-looking fringe. Without luck, I've got nothing. So I try layer 2 and layer 3. Once I've got something usable on the clipboard (the imaginary space where copied things go), I erase the blocks from layer 4 and replace them with identical blocks in layer 0. At this point, the blocks will look 2d. Then I go to layer 5 (usually), and paste the fringe I grabbed earlier on the edge of the layer 0 blocks. Presto! It looks 3D, but Jack can go through it like it isn't there.

You can paste the fringe in layers 1 through 3, but it usually messes something up. Same for layer 4, really, but if you want to do something complicated like what you've got in the screenshot, you'll have to use at least two layers.