In some if not all of the Starter Solutions
Please point out a particular Starter Solution you have in mind.
Sorry I was away,
Yes the ones I was thinking of was the Content Management and really also the Contacts versions.
In Content Management, the popup has a hardcoded value list of sorting options; after selecting an option, an OnObjectSave trigger starts a script that has a number of If  blocks with diverse sort orders and branches depending on the current value of the popup field. Go to Layout mode and inspect the script trigger for the selection popup, then open the script in “Manage Scripts”.
Haven't looked into the Contacts file, but I suspect they use the same technique there.
Ok thanks for that I'll take a look.