Drawing Diagrams

Hi all!

  I am sorry if this question has been repeteadly asked before but I am a
newbie in this field and I need your advice:

I am trying to build set of components to draw digrams (as UML diagrams) but
for other methodology.

I cant manage the problem of having nested components and arrows linking
them to other components due to the clipping of each component canvas.
May be the whole approach is wrong... May be I should use double buffering
and simulate the dispatching of mouse behavior and such but I was trying to
avoid doing all that myself.

I am using TGraphicControl as base class, to avoid comsuming tons of
resources,  and also because it already provides the event notifications and
they are very easy to customize.
I handle the nesting of components myself, since TGraphicControl is not able
to do that.

Any link, tip, technique, book or example is welcome!

Thanks a lot!