Ok, now you must be wondering what is xcorrect and ycorrect? They are
nothing but simple variables to correct the X and Y coordinates of the
MovieClip. If you use HitTest without making provisions for Xcorrect
or YCcorrect, you may not get the desired result.
When you draw something and then convert it into a MovieClip, you will
notice that a small circle appears at the centre of the MovieClip.
This centre actually acts as the X and Y coordinate for the Movie. You
can picture it like this:
You can see that the X and Y are located at the centre of the
MovieClip whereas it should have been at the top left-most corner. So,
to get the actual X and Y co-ordinates, subtract half the MovieClip's
width from its _x co-ordinate and subtract half the MovieClip's height
from its _y co-ordinate.