In gVim 9.1 how to have different backgrounds for text and the empty area to the right of <EOL>, with hlsearch ans syntax highlight still working?

Question

I would like to use two different backgrounds colors bg1 and bg2 with:

1. bg1 for all text on a line (possibly nothing if line is empty) up to the end-of-line,
2. bg2 for the empty area after the end-of-line,
3. while keeping hlsearch working,
4. and syntax highlighting working.

For example, if displaying <empty_area> as _'s starting with # on a 16-character-wide window, with "text" as the search pattern and a syntax recongizing if, it would look like:

    if "text"#______
    #_______________
        indented#___

with:

• anything but the trailing _'s with a different background (here black foreground)...
• ...than the trailing _'s (here gray foreground),
• except for "text" which should be highlighted as the Search group (here green foreground),
• and if which has the syntax highlighting of the chosen language (here blue foreground).

I have tried this in my vimrc:

hi Normal     guibg=Gray75
hi Contents   guibg=LightGray
match Contents /.\+.\@!/.

but then I lose the pattern match highlighting for hlsearch, which is I guess superseded by the Contents match.

Is there a proper way to achieve what I want: different backgrounds for text and empty area after EOL, with hlsearch and syntax highlighting still working ?

PS: The NonText group is not relevant, since it links to the empty area after the buffer, and not after each line.

Answer 1

I tried adding those lines to my .gvimrc file:

    hi Normal     guibg=Gray75
    hi Contents   guibg=LightGray
    match Contents /.\+.\@!/.
    noremap * *N:2mat Search /<C-R>//<C-M>n

which solves the hlsearchissue. But the highlighting involving background, like with diffvim, gets broken. So I fell back on this lighter solution:

    hi Normal       guibg=Snow2 guifg=NONE
    hi Contents     guibg=Snow1 guifg=NONE
    2match Contents /$/

which highlights the first non-character at eols and is finally noticeable enough.

Answer 2

I would do:

highlight SpecialKey guibg=LightGray

highlight Conditional guibg=LightGray
highlight Content guibg=LightGray
highlight Exception guibg=LightGray
highlight Function guibg=LightGray
highlight Include guibg=LightGray
highlight Operator guibg=LightGray
highlight Repeat guibg=LightGray
highlight Statement guibg=LightGray
highlight Structure guibg=LightGray
highlight Type guibg=LightGray

highlight Content guibg=LightGray
autocmd FileType * syntax match Content /\S\+/