1. In Transfer Settings, allow several (e.g. 2) transfers at the same time, and check "Transfer on background by default" and "No confirmation for background transfers".
2. Select a remote folder with many files.
3. For testing purposes (and so that you won't be sorry for its loss), create a local copy of it.
4. Move it to another local folder in two threads, e.g. by standing on the folder and pressing F6, Enter, F6, Enter, in quick succession. (This is a simple way to reproduce the error, but there are more sensible ways too.)
Now compare the contents of the two folders: the original copy, and the one created by moving it. Most of the time, several files will be missing from the latter.
I took the time to write because I think it is a high priority bug to fix, as it involves possible loss of data.
- Windows XP, with latest service packs
- latest WinSCP (4.3.6., Build 1655)