To increment a date?

The easiest way (for the most part) to tell a SCALAR from OBJECT is… ask yourself…

“In normal use of this datatype am I supposed to use the ‘NEW’ keyword?”

If the answer is yes… it is not a scalar

Wiki

There are a few non-scalars that you don’t use New with, such as FolderItem and RecordSet. They are objects, not scalars, but it doesn’t make sense to simply make a New one, you have to call a method that creates a functional object.

That is true… which is why I said “for the most part”…
and if the answer is “YES” then it is an object… not meaning to say (as you indicated) that an answer of NO meant it was scalar.

and technically STRING is an object as well (not requiring NEW) because it does have encapsulated methods

The scalars in Xojo are numbers and strings. Everything else is an object. And while as Dave points out, a string technically is an object, it acts like a scalar due to restrictions imposed upon it by the language designers.

I was under the impression that colors were also scalars.

Yes, I forgot about colors.