The IBX for Lazarus Source code can be browsed using:
https://svn.mwasoftware.co.uk/ibx
You can also check out the latest release using
svn co https://svn.mwasoftware.co.uk/public/ibx/tags/R2-7-0 ibx
The latest version of the source code including recent patches can also be checked out using
svn co https://svn.mwasoftware.co.uk/public/ibx/trunk ibx
These are tested fixes and recommended for all users.
You can find out more about subversion from here.
The up-to-date ChangeLog for IBX is available here.
The up-to-date Change Log for fbintf is available here.