extend the API to expose the background colour of the Right Sidebar

[hiccup]

Here is a request for something that I won't be able to use or implement myself.
But I expect it to be something that is useful to the creators of a couple of plugins that I am using, so in the rebound this is a request that (I hope) will benefit me.

I usually place (visual) plugins in the right sidebar panel.
But when I do, most will not blend in there because their background colour differs from the sidebar panel.

After some interaction with BoringName about this I came to understand that it can't be done at the moment because MusicBee's API does not provide an 'element' to use the background colour of the right sidebar.

So the request is for the API to be able to provide it.

For skins that use the available elements for this panel, it would be the bg of "ElementPanel.Default".
For older skins or skins that don't use that element it should probably fall back to a lower order element.

While at it;
If some additional positions for such plugin panels are to be considered, there would be two other candidates that could be useful for the API to expose:

- Content[Artwork].Body.Default
- ElementPanel.Default

see here for the reasoning on that

Some plugins (and their creators) that could benefit from this:

VUMeter by BoringName
CoolEdit Nostalgia by kamen
Library Quiz by Mayibongwe

There are probably more, but these are three that are created and maintained by very active and agile forum members/plugin creators.

(so I will probably start bothering them when this request gets fulfilled ;-)

[hiccup]

solved