Mel;
    Regarding Issue 3.  One possible way is to find the midpoint of the line
[(x1+x2)/2],(y1+y2)/2] and see if  that point is inside or outside the
polygon.  Now take the line segment (half the original line) that includes
the edge of the polygon and repeat the process (if the midpoint is inside,
you want the outer half of the line. If the midpoint is outside, you want
the inner half of the line).  One can repeat this process as many times as
necessary to determine the intersection point to whatever accuracy you need.  

                                                        Eric
                                                        Argonne National Lab

>3. Next in my list of things is simply this. I build a region (good old
>fashion polygon). I know I can test to see if a simple X/Y point resides
>within the region. Not a big deal (gotta love the Mac toolbox for helping
>out!).
>
>However. assume that we have two points (with a line connecting them). One
>resides in the region and one is outside the region. In plain English,
>using 1K words or less, is it possible to tell at what point the line
>between the two points, meets the edge of the region (and convert or get
>that point in X/Y coordinates)?