keynav deactivates when it is small enough

[wgmayer0]

I don't understand why keynav disappears when it gets too small?

If you zoom in too close and make the 4 quadrants small enough, they completely disappear and hitting any key doesn't do anything.

Why is this the default behavior? What it should do is stay at the smallest pixel so the user can undo history or click at the pixel where the pointer is located.