Thank you! That clarifies several things I'd been doing instinctively in the bordered versions, that I hadn't extrapolated into conscious thought for the wrapping ones. I shall tackle them later. (Not now, not at work. Really not. Honest. I can resist. *cough*)

Now all I need is a "lock" option for tiles so I don't forget which ones were set that way for a reason darnit... ;)

Middle-click, or shift-click if you don't have a middle mouse button.

Woo! Excellent.

And I just solved one, too *beam*

Oddly, that has made more difference to solving the wrapping ones than anything else! Much obliged :)