[LyX/master] Introducing color themes

[Koji Yokota]

> 2025/03/02 23:07、Scott Kostyshak <skostysh at lyx.org>のメール:
> 
>  support/FileName.cpp (464): Directory '/home/scott/lyxbuilds/master-master/user-dirthemes' does not exist!
> 
> The message goes away with the following change:
> 
> -       usr_theme_dir.set((package().user_support().absFileName() + "themes").c_str());
> +       usr_theme_dir.set((package().user_support().absFileName() + "/themes").c_str());
> 
> But I don't know if the fix is needed elsewhere or more centrally. Any idea?

absFileName() gives trailing slash on Mac but it seems not true on some other systems. I’ll check and fix it soon.

Koji