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.