Thank you for replay. No, I don't use clone regions, I don't like their behavior. I normally do a copy of a region. I'm working with regions in my arrange window where the whole project is.
If I wish to see exactly what I'm doing by time stretching a region I have to do this in my arrange windows. But time stretching a single region affects also all other regions that belongs to the same audio-file in the same project. But also if I don't have a copy of that region in my whole project my original audio file is in any case gone for ever.
I would like Logic to automatically create a new time stretched audio-file living the original one untouched. How can I do this? As written in my post to manually bounce the region creating a new track (and new audio file), perform time stretch on this new region, put this new region back on the original track, delete the track just created by the bounce is a huge waste of time, is it not?