V3 - Theme editing - esp. toolbar backgrounds, borders etc.

As noted elsewhere, scroll bar widths are wrong for the default theme. but better in all the others I tried - except I don’t like any of the others. Also, most modern themes are a bit “flat” for my liking and don’t distinguish areas strongly enough - but that’s all a matter of taste, and that’s why themes exist

So I thought I’d pick some other theme with good scrollbars and edit it to my liking. Doesn’t seem to work - looks as though there are things in themes that are not accessible to the user.

I have investigated every option I can find and can’t see how to set toolbar background colours (or tool bar element border colour/thickness).

I even managed (finally) to save a theme and inspect the scrtheme file… only to find that unlike prefs it is ~binary, or at least not human readable.

What’s the best way to proceed to get the UI that I want? It is a fact that all the functionality in the world is for naught if one is not comfortable in the interface that provides it.

Thanks, Julian