I didn't write the WinMX program either but that doesn't stop me from knowing a few facts about it.. so let me clarify a few things for you as well.
Incomplete files Do get listed in the search and browse windows, but although I have que'd them, thousands of times, I have never seen one actually upload (in the last 4 years).
Of course the file must have at least 1% completed for you to be capable of downloading that %, but I assure you it will in fact download. WinMX will then tell you that you have received all bytes available, not a sharing violation. Try it
WinMx doesn't auto store DLed data parts to their component files, as some is stored in incoming buffers; so the file listed (if actively qued) is an open file and would probably trigger an 'application sharing violation'. It is not even a good idea to preview files in this state. I would even guess that interfering with an open file might lead to a corrupted data stream and increase cpu usage (tracking a 3 way stream).
WinMX does INFACT save DLed data to its settings.dat file so the file is not an open
file as you state. It is perfectly ok to not only preview them but to move them, store them on removable media and re rip them to the PC to use again, share them or download them.
WinMX keeps a minor bit of data (you can get the techie words for all this from my other half I'm sure) telling it where it left off on the download and if that bit of data is lost for some reason, sudden shut downs or power loss is known to cause it, then it will remember only the last time it had such information stored on that file. Hence trimming 10K a few times will rectify this situation as well.
...when the file is complete, it is renamed (minus the hash). At that point the 'users share library' has to update with the new file name and get the correct hash, or at least confirm it. This then has to be updated to the primary servers indexes upline, for filename, location and hash.
The file is in fact automatically renamed when its completed and yes the update is then sent out to the primary client (if you are secondary automatically for WinMXv3.54 and next refresh for older WinMX Version) however, your wrong about it getting a new hash. I assure you that incompletes are given the hash they will always have on WinMX, changing its name doesn't effect this and neither does the fact that its become complete. If your thinking were true this would destroy the multisource downloads that the WPN offers by rehashing files every time they finished. Do some searches and you'll see that incomplete files indeed to match the completed ones shared by other users, if the source was the same to begin with. Take the hash of an incomplete you have that has other matching results and do a search.. you'll see they match completed files.
I hope that you'll do some searching and see for yourself about these things.. its quite clear its entirely possible to download incomplete files, although like Bearded I dont normally share said files.