Resize Line Object at Runtime

I need to be able to allow users to resize a line object on a screen at runtime. Is there a way to get the form mousedown event or an API to recognize a line object if a mousedown occurs within about 60 twips of the line object? Once I get the line object index number I will then place little picture boxes at each end to handle the resizing.

Or would it be easier to create a line object with the appropriate events. Any examples of this would be greatly appreciated.
Thanks.

I think what I would do, is use API to draw the lines based on values stored in an array. Using PtInRect could check for mouse proximity, but if the lines are equally spaced, you could just calculate which one is nearest the mouse. You could also use API (or shape controls) to draw the resizing rectangles.