Was searching for goodie huts with my Sovereign when i saw another Sov. coming into view a few tiles away. He built a city almost directly in front of me and wandered off, not immediately realizing that, i mistook it for another hut and tried to move onto it which of course opened up the new choice window. Not wanting to deal with him right now, i tried to move on, but with only one movement point left (found 2 agility rings) i only managed to move from directly west of the city to the northwest corner. Next turn the borders show up trapping me in that tile, clicking outside the borders resulted in no action, clicking inside once again gave me the option to declare war or negotiate.

Sadly i couldn't test further because tabbing out to check if the screenshot actually was taken resulted in a black screen when tabbing back in.