The worst thing about the WPS is that its most central operations are largely undocumented. It is nearly impossible to find any documentation about what the actual file operations methods (wpCopyObject and such) actually do, who calls them, and what all these WPS threads are doing.

To find out more, I have done an extensive debugging session tracing the method calls during a copy operation. You can find the whole log in the logs\copydrag.log file. The operation which was logged was a Ctrl-Drag (copy) of the "check.c" file within the same folder so that the "File clash" dialog (actually, my replacement) comes up, the target object is renamed, and then copying actually starts.

During this operation, I roughly got the following: