Patch for a change set?

I just tried to create patch for a change set, and found that system compared the version of file in the change set to its original (zero) version instead of previous one, does this make sense?

No it doesn't make sense. If a changeset CS transforms a file A from A1 to A2, there's no point creating a patch with the difference of A0 to A2. However, if you you are trying to apply it to that file in state A5, then you have a mixture of three files involved, none of them being in any way a zero version though (at least not necessarily).

I'd say I don't understand what exactly you were doing that brought you to that conclusion, but I guess it's was confusion caused by the merge editor that makes it way too easy to merge code into your sandbox that was not part of the changeset. ;^)

Uli