[Lazarus] pointers in writing extension for Lazarus

[ik]

Hello,

For a very long time now (7-8 years), that I wish to add Lazarus
possibility to split edit of my current edit (and other open files)
vertically and horizontally.
I understand that many people here don't like the idea, so I wish to
write an extension for, rather then adding it to the UI itself.

Can you please give me some pointers in the matter on how to start
writing it, what should I be looking for etc... ?

Thanks,
Ido