gravlax wrote:However, it will not open .kdb files created by regular Keepass.
I don't have a Mac, but in general you have either a version of KeePass that can open kdb (version 1) files and not kdbx (version 2) files or you have a version that can open kdbx files and import kdb files. It's important in the later case to use the import routine for the kdb file instead of just opening it, because the format changed dramatically between version 1 and version 2 of the database file.
You also need the latest version of KeePassX (version 2, alpha 2 or higher) to support importing kdb files. Importing kdb files was not supported in KeePassX version 2 alpha 1. Keep in mind that KeePassX version 2 is still in alpha release, and they focused on database version 2 support (kdbx support) with the first release, not backwards compatibility with database version 1 (kdb).
If you work solely with kdb files, you should instead use KeePassX version 0.4.3, which fully supports kdb files, but cannot open kdbx files.