After saving a file, it can be modified without checking it out through Team Coding.
1. Enable Team-coding.
2. Open any PL/SQL in Editor.
3. Object is Read Only as it should be (not checked-out).
4. Save to a file.
5. Object becomes marked as "uncontrolled" and can be Edited and Compiled. Object is not checked-out.
Fixed in version 9.5.
The latest version of Toad for Oracle can be downloaded at the Support Portal.