Got most of the GUI working, with the exception of exiting the Box. I've traced it to a bug in the function: calculateHeadingForExit, where I think None is returned to target. This is a problem because target, if none, crashes for adjustSheetsForExit. I will inspect how the original version avoided this problem.
Merge remote-tracking branch 'origin/StationKeeping_Cleanup' into StationKeeping_Cleanup
Got it working! The problem was a missing line from the original code which returned an angle for Compass Method to target, in calculateHeadingForExit.