Use case or problem
As I update my PKM to integrate properties, I see that for certain note types I want to include a relatively large number of properties. Conceptually, these cluster into related subcategories (e.g. for daily notes on reading a book, some properties like book, section, depth of study etc. fall into a subcategory about my engagement with the book itself, and others like time and place fall into a subcategory about the context in which I was reading). However, just having all of these be listed together in an undifferentiated list / table can make it feel a bit unwieldy or jumbled visually when the number of properties starts to get large.
Proposed solution
To handle cases like the above, it would be nice if there was some minimal level of customizability of the properties UI which allowed for visually breaking up the properties into subgroups, even something as simple as the option of adding line borders to selected rows of the table, or being able to customize spacing or background color etc. for selected parts of the table. Before properties came along, I had metadata at the top of my notes as lists of inline dataview fields and accomplished this visual grouping just by adding empty lines between groups.