What's Wrong with my UV editor? I've been working on this scene for a long time now but as I tried to put a skydome in, it would keep denying me the ability unwrap the top half of a UV sphere. I tried doing the same thing in a brand new scene and it worked, but not in the one I am currently stuck on. 

The UV editor is more of a rectangular shape than normal, which I believe is part of the problem. Basically I am asking how I can fix this so I can unwrap the top half of a sphere to create a skydome.
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