Err
I mean, that black one in the top left still works like a transparent tile, but appears black in the viewer.
The other stuff there with black background is transparent in Paint.NET, but appears comepletely black...
I'm going to try the whole magenta thing, forgot about that.
EDIT: Hmm, crap. Now it says 'fully transparent tiles were found'
EDIT 2: Actually, I'm probably being stupid and have just thought about why that's happening and am going to fix it.
EDIT 3: Fixed, feel free to ignore me now
/fixes own problems
/is useless