Hi Xberk !
Yes scrolling with the mouse wheel, up and down to display tracks that are off screen, it's very useful when you have a lot of tracks, like 10 or more. In reaper you work on track number 1 then if you want to work on track number 10, you just scroll your wheel mouse while the mouse cursor is located on top of on the left part of the tracks, and it brings you where you need.
What I mean by "left part of the track" is the part on the left of each track, the one with only settings, the right part is the track itself, on the timeline.

I don't know of way to duplicate the Reaper behavior in Vegas but if you highlight a track header (on the left) you can use the up and down arrows to scroll up and down all the tracks. Otherwise there is the vertical scroll bar on the extreme right that will slide the tracks up and down (or click on the + or minus sign or up and down arrow symbol). If you double click the vertical scroll bar slider, the tracks will minimize so as to see as many as possible at once.

Thanks Xberk !
Is there's way to assign the scrolling while on top of the track headers to the vertical bar, with the help of "customize keyboard" in the option menu ?

Edit : There is one more way : If I hold Ctrl and scroll, it moves the timeline vertically. I really would like to be able to do it, just with the mouse scroll. Maybe with the help of macros and the "Customize keyboard" feature. Is there an equivalent of the Reaper "Action" menu in Vegas ?

>> There is one more way : If I hold Ctrl and scroll, it moves the timeline vertically.

Never knew that .. or if I did, I've forgotten. Thanks.

You're welcome :)

@Marty111 If I hold 'Ctrl' and use the mouse wheel it scrolls the tracks up and down, is that what you want to do?

I think the OP says above that he'd prefer to just scroll. These are some of the default shortcuts (some of them mentioned above)

@vkmast I don't think those keys can be re-assigned can they?