How can I draw a control alignment indicator like Delphi XE2?

Question

I have a Delphi 6 program that allows the user to drag controls around the page. I do it by using the following code in the MouseDown event.

ReleaseCapture;                              
TWinControl(Sender).perform(WM_SYSCOMMAND,$F012,0);

How can I draw a set of lines aligned with the left side and the top of the object being dragged so the user can align the control with other controls (similar to the XE2 design)?