license recommendation

[Mr SZ]

Hello everyone,

My friend is planning to release a set of free activeX controls .He wants to know if there exists a license which :
If the end user is a developer,then he can ask for the source code and if the developer makes changes/improvements,he is required to submit the changes  back to him.

Now he wants to know if any such open source license/shared license exist which will fit his criteria.   

PS:If I buy the source code of a program,does it mean I own the code or do I just have the right to own it and modify it to some extent or something else?
  
 Send instant messages to your online friends http://au.messenger.yahoo.com 
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.opensource.org/pipermail/license-discuss_lists.opensource.org/attachments/20070418/e9c64ad4/attachment.html>