Custom RTE Style Groups

Questions
1

Y’know how the default Styles dropdown in the Rich Text Editor looks with the Headers, Blocks, and Containers categories?

How do you accomplish that with a custom rich text style sheet?

There doesn’t appear to be any options for grouping sets of styles like this in the editor and no instructions in the documentation for it. Whatever you add for to a styles just gets all dumped into a single one-level list.

Is it possible to do OOTB?

(Workin’ in v12/v13)

Edit: Just found the rte appsettings. But it looks like it’s all hardcoded options. Is there a way to have it pull from values setup in a style sheet?

This is a companion discussion topic for the original entry at https://our.umbraco.com/forum/113353-custom-rte-style-groups
2

I just stumbled on this question because i have the same issue.
We have added a custom stylesheet and the default styles disappear.
So our main goal is not to group the new styles but to keep the default along with ours.
Does any one know how to do that?