AutoShapes

Could anyone provide me some infomation regarding how to design the following task...

I am try to design a rectangle linking system (something like Word "AutoShapes" or Visio)

+----+       +----+
|      |---->|      |
+----+       +----+


1. Create multiple Rectangle control (may be buttons, images...) in a panel, each rectangle has 8 linking points (show as below)

a-----b-----c
|              |
d              e
|              |
f-----g-----h

2. User can drag any rectangle to anywhere in the panel

3. There are few arrow lines link rectangles

4. User can draw new lines or change existed lines between rectangles by using mouse, during user drawing a line, if the cursor is closing any rectangle (let's say 15 pixels), the program should connect the line to the nearest linking point automatically.

Thanks