Background Extending?

I have this really odd bug involving the background on all of my campaigns. It tries to extend itself until I scroll all the way to the far edge of the bar. The top picture is when I'm scrolled all the way to the bottom of the canvas, and the bottom picture is when I'm scrolled only slightly away from the bottom. You can see the extension of the medium gray background. It's not just vertical scrolling that does it either - horizontal scrolling also shows this effect. I'm running Windows 7, Chrome Version 42.0.2311.135 m

This is a known bug, which has been there for a long time. I'm not sure where it is on the Dev's list-of-things-to-fix, but it's on there somewhere. Annoying but not game-breaking; we learn to deal with it. -Phnord

It's a graphical issue. The map is not actually expanding, it just appears that way temporarily to you. It is a known bug and on our list as Phnord said.