[Ben]

In edit mode, setlists have an additional (first) column that shows the sequence number.
I think this column would be useful in the regular setlist view as well. 
Three applications I have in mind:

When editing long setlists, I "toggle" between edit mode (add/remove/reposition the songs), and regular view (check whether a song truly fits in that position, looking at the details of the neighboring songs as well). The sequence # in the regular view would accelerate the process of giving each song its proper position. 

When you rehearse a setlist with others, everyone finds the song back quickly if you can just say, "go to 22". 

I missed the sequence # in this super-long-sing-long session recently when people browsed through the super-long-sing-along setlist and requested songs. Sure, a setlist can be sorted alphabetically, and I probably should have set it to that for that specific session, but then you lose the carefully chosen grouping of songs within the setlist.

Would this be possible without major efforts, Mike?

Thanks.

[Zubersoft]

The level of effort isn't too crazy, but it isn't an easy five minute fix unfortunately. I actually added an enhancement request for this awhile ago so I wouldn't forget about it, but with my focus on finishing the Windows 10 version, I haven't had time to address it yet. I believe it should be something I can finish in a night or two once I start working on it.

[jdp72]

The level of effort isn't too crazy, but it isn't an easy five minute fix unfortunately.  I actually added an enhancement request for this awhile ago so I wouldn't forget about it, but with my focus on finishing the Windows 10 version, I haven't had time to address it yet.  I believe it should be something I can finish in a night or two once I start working on it.

This is also a solution for my request to hava some sort of ordering / grouping in a setlest.

e.g. if the numbering could be something like 1.1 (set 1 song 1) and 2.1 (set 2 song 1) it would be a great addition.

[itsme]

You do NOT lose the manual order of the setlist, when you change to "A-Z". If you switch back to "Manual" the previous manual order is back again. 
I often use this during rehearsals.
Once again: Mike did an excellent job and considered many helpful details.

[Zubersoft]

The level of effort isn't too crazy, but it isn't an easy five minute fix unfortunately.  I actually added an enhancement request for this awhile ago so I wouldn't forget about it, but with my focus on finishing the Windows 10 version, I haven't had time to address it yet.  I believe it should be something I can finish in a night or two once I start working on it.

This is also a solution for my request to hava some sort of ordering / grouping in a setlest.

e.g. if the numbering could be something like 1.1 (set 1 song 1) and 2.1 (set 2 song 1) it would be a great addition.

That requires far more complex changes than just displaying the number. That would be a separate change as it would also require a lot of changes to the editor to support creating those sub-groups inside the setlist.

[Ben]

@jdp72, the 1.1, 2.1 numbering would require some additional input from the user I guess, while the simple sequence # can be generated automatically.
@itsme, yes, this is precious (the manual sorting isn't lost), still a temporary alpabetic setlist will always be void of much of the original setlist character, where one part of the setlist is perhaps just "The Police" songs, another is songs from the 90's, a.s.o.
For me, the sequence # would add value to an already invaluable App...
Mike, Windows 10 MSP will make a larger group happy, so I'm prepared to wait!