Can Lar give to foreign developers source codes of game for writing add-on? Or any other way...

Larian is still updating the game, after the recent Steam and Larian Vault releases, so I doubt they would release the source code. There are modding tools being included with the upcoming Divinity: Original Sin, though.

Ok....waiting Divinity: Original Sin =)

The fact that modding tools are being included with Original Sin is BIG.

If a loyal modding comunity starts to develop we'll be enjoying the game for countless of hours...Which I dig.

indeed)

Yes... But Divine Divinity is one of those magical games that I enjoy playing again and again. And I'd love to have a possibility to play a little more next time.

A while ago someone from the Larian Studios digged up and old ingame chatlog or something like this, where the developers discussed the process of programming and the code in general.

I´m too lazy to look them up right now (maybe Raze can, if he remembers) but the way they talked to each other back in the days kind of displays their way of programming, that sounded something like this :
" Wtf, is this shit" "Bullshit ain't workin wtf u did there ?!" "This sweetshit looks good but crashed all the time <_<"
"How the f*** is this even working ~ whatever"
I guess they were young forward looking people with many many ideas but the problem about making an addon or giving the source codes to the users is, it wouldn't make any sense to us at all.
The effort and pure lunatic power that went into this game ended up in an very beatiful and epic game with a VERY fragile and (sometimes) bugged source code.

I'd really like to see Larian Studios remaking the game but since they won't run out of ideas soon you may satisfy your hunger with some background information and eastereggs you didn't find yet :
The guy who designed the characters and some animations :
(http://valaraukar.de)
Eastereggs and secret areas :
(http://www.larian.com/forums/ubbthreads.php?ubb=showflat&Number=77614)
My favourite :
(http://www.xanlosch.de/kiyas_crypt/Div_Skateboard.jpg)

Some comments in the game's code were quoted (slightly edited) in the topic Status update (long overdue).