I did this in a funny way (sets the environment for the process).
The idea is that any code which sloppily used Path.GetTempDirectory (etc.) would now have its pathing changed.
It is a little dangerous to allow this to be changed on the fly (I do allow it) since something may expect it to be stable, but I think it's OK.
So anyway. keep your eyes peeled for problems. It's possible I could do this differently and only affect a subset of safely managed things.
should fix#1252
ba4b32f619