Visual Studio - Color Theme Designer: Selected text wrong background color

Question

I'm playing around with the Color Theme Designer for Visual Studio 2022 to create a custom color scheme.

I have come to a syntax highlighting I like so far. But then I noticed that the background of some selected text remains at the normal background color (here: 0x282828) over keywords like new etc. See the screenshot below.

For that selection background I set up the All elements category in Color theme designer like:

Text Editor Text Manager Items
    ...
    Plain Text        07282828
    Plain Text        FFEBDBB2
    Selected Text     FF076678
    ...

The property Selected text occurs here twice; once it probably concerns the background color, the second time the foreground color.

But on the screenshot it is visible that the background color only is applied to the empty glyphs, spaces etc.

Which setting in the Color Theme Designer must be changed to get the selection background color applied to the whole selection?