Dark conical shape appeared in solid view clipping display of objects I was setting up a render border, but instead must have pressed something wrong (I'm not sure what) and this is what I ended up with:



Basically, there is a darker, conical or pyramid shape in the solid view and it restricts (clips) what parts of items are visible.

I want to disable it, but because I don't know how it is called or what I did to enable it in the first place, I can't find the option. 

What is this feature called and how to disable it?
By accident you set View Clipping Border with Alt+B shortcut, to disable it hit Alt+B again.