Group window manager themes by category

The theme list in Settings → Window Manager → Style is a flat list, which gets long once distribution themes and user-installed themes are added. It’s hard to tell which themes belong together.

Proposal 1

Add an optional key to each themerc file:

theme_category=Kali

The Style tab would then show themes in a tree, grouped by category, with collapsible rows:

▾ Xfce
    Default
    Daloa
    Kokodi
    Moheli
▾ Kali
    Kali-Dark
    Kali-Light
▸ Other

Themes without the key would go into a fallback category such as "Other" or "Custom". The bundled themes could get theme_category=Xfce so the grouping is useful right away. Kali for example can than add a key to it's themes.

Proposal 2

After Proposal 1 is implemented it would be awesome to add the old Xfce themes from https://archive.xfce.org/src/art/xfwm4-themes/4.10/ or even older ones from https://archive.xfce.org/src/art/xfwm4-themes/ as a GitLab repo to the project. Most of them look really cool and are a piece of art. It would be cool to have them in an upcoming Xfce release (or as a separate package) with their own category like theme_category=Xfce Originals.

I’m willing to work on a MR with the help of AI if the idea is acceptable.