Returns true if the endpoints of this line match the endpoints of the specified line, ignoring endpoint
order (if the first point of this line is equal to the second point of the specified line, and vice
versa, returns true).
Flips this line so that the end points are reversed (in other words, (x1,y1) becomes (x2,y2) and vice
versa) and the normal is changed to point the opposite direction.
This is the 3rd version of SwingWorker (also known as SwingWorker 3), an
abstract class that you subclass to perform GUI-related work in a dedicated
thread.