Disable theming of statusline separators

[luetage]

This pull request disables the theming of statusline separators introduced in #3175

The reason: To my knowledge none of the existing themes actively themes separators. Additionally there is only a way to theme the separator in the active statusline, the inactive statusline separators will always use the foreground and background color of the active statusline separators. In practice this leads to faulty theming of foreground and/or background color of separators in the inactive statusline, depending which colors themes set for main fg/bg of active/inactive statusline and whether there are differences.

[sbromberger]

FWIW, I'm against this reversion as I use a custom theme that has a separator entry.

The addition of the theme element hurts nobody; themes that choose not to use it don't suffer as a result, and it provides accessibility benefits for those folks who decide to customize.

If the active/inactive issue is really a problem in practice, I'd prefer to see separate theme entries for active and inactive statuslines.

[luetage]

@sbromberger It is a problem, because it breaks the display of separators in almost all themes. The only exception are themes which use the same foreground and background color for active and inactive status line. Anybody who uses a separator is affected and it’s only fixable by writing a custom theme and setting fg/bg of the separator to an empty value: "ui.statusline.separator" = { fg = "", bg = "" }

This could be fixed by providing a theme entry for inactive statusline separators, but then the question arises why separators are the exception. Shouldn’t we be able to theme every single possible statusline element for both active and inactive statusline following this logic?

In my opinion it adds unnecessary complexity, when in practice the statusline should be simple to both set and theme. In any case the current implementation is buggy and needs a fix.

[sbromberger]

Why don't other statusline elements (render_mode, workspace_diagnostics) have this same issue?

[luetage]

I haven’t seen render mode in statusline, but both workspace diagnostics and file diagnostics reuse the diagnostic colors for the dots and the counts use default statusline active/inactive theming. I guess the only thing you have to be mindful of as theme creator is assuring enough contrast between your chosen statusline backgrounds and the diagnostic colors.

[chtenb]

Yes, separators are currently not reasonably usable due to the lacking inactive setting. Removing them seems indeed a correct patch until a better set of theming parameters is introduced.