Consider visual feedback when Move Map isn't allowed (mdv2+) because you're at the border

[shannonturner]

In mapDataVersion 2 and above, if you try to Move Map all the way to the edge of the grid and beyond, it will stop, refusing to allow you to lose any work.

That's a good thing, but it doesn't give any indication that you've hit the border -- it just stops.

Might be good to show something on the hover-canvas or the button, like a visual bell or something.