Steps to Reproduce:
1. Menubar -> Tools -> Options
Firefox themes will be updated from mozilla.
Preinstalled Themes with configuration dialog and theme per app or for all apps.
User Profile Reset: No
Created attachment 151607 [details]
LibreOffice Theme dialog
main view very simple with previews and option for theme per active app or all apps.
configure for each theme is possible for different items.
Toolbar, Statusbar, Menubar and Sidebar
You can configure the Area (like area drop down menu) and Font.
I would prefer the solution from bug 125217. And if you disagree your mockup would be better suited there as an alternative. => DUP is my take
*** This bug has been marked as a duplicate of bug 125217 ***