Yes but, 'self theme' is 'the theme engine that defines all theme settings' and
'self theme backgroundColor' is
'what this theme defines as general backgroundColor'
It does not mean that self (the morph) is actually using this theme setting for anything.

I know, I don't care if the morph itself uses it somewhere or not, I wanted color that _should_ be used as a background, so I can apply it to some part of the morph myself.

it is the general background color (that should be applied *by default* to all morphs that recognises the background property), as Nicolai pointed.��

Yes, that is what I was looking for.

I used the self theme backgroundColor and it works for the time being.

Peter