I understood your issue was about being able to see the changes you may have made outside Code::Blocks if the "file has changed" dialog pops up. However, the last post sounds like your intent is to check for modifications every time a file is saved, because two developers work on the same set of original, non-versioned files at the same time.
I don't think this should be implemented in Code::Blocks at all, since it is silly. If you have two users modify the same original source tree concurrently, then honestly, you deserve conflicts.
Use Subversion, that's what it is for! It works reliably with 2 people (or with 2000) working concurrently, and it offers a big deal of other useful functionality (for example having a commit log, or the ability to go back in time, or the ability to track who did what change, branching, ...).
Subversion (or another RCS) is even useful if you work on a project all alone, but for any serious project with more than one developer, it is absolutely mandatory, there is no way around it.