How do I monitor files in the folder but not its subfolders?
Starting with version 2.2 CallbackFilter supports pass-through rules. These rules let you specify masks, for which matching files are not handled using other rules (i.e. are excluded from filtering).
So if you want to monitor "c:\some_path" but not it's subfolders, add a regular callback rule for "c:\some_path\*.*", then call AddPassThroughCallbackRule() method and pass "c:\some_path\*\?*" to it. This will exclude all files in the subfolders from filtering.