Hello, I have some voice over tracks from a seminar.
Each track is divided into numerous clips.
I want to apply non-destructive fade-in & fade-out (like the ones we can apply when a small triangle appear to the sides of the clip) to all clips.
Is it possible to apply that, massively to all clips?
Like making/using a macro or something like that?
Thank you all in advance,
Kostas
(User level: medium) 

Yes, select all the clips, hold the Ctrl key while applying the clip fade to one of the selected clips

Oh, so simple!?
Thank you Scoop!!!
You save me so many hours!!!
Thank you!!!

I can also confirm that the Shift key can do the same job (at least in older versions) very well too!
Thanks!

envelopes?

When dealing with fades on scores of clips, using envelopes would be tedious (by comparison).
 
Note that you can also change the slope of the clip fade (slow, linear, fast) "en mass" by holding the Ctrl key.

Yeah, using Ctrl with a selected a group of like objects creates a quick group for manipulation. Many objects in SONAR respond to this technique.