I have been attempting to change colors on my desktop. My research into how to do this has suggested something and I needed to know if this is true because it seems really odd.
I am under the impression that the windowing system for almost all things linux is X11. Is it actually impossible to alter the colors of window borders in x11?
It seems no matter what flavor of linux or theme you are stuck with ugly black or white.
Why this seems odd to me is i cut my teeth on an Amiga 1200 which has been dead for 30+ years and linux has made me feel like I took a step back into the 70s.

My window borders with adw-gtk3 (and a Gradience theme preset) on Budgie are not black/white but some sort of gray. So no, doesn't seem to be impossible in principle. Now what options are supported depends on your desktop environment, theme, the app's used toolkit, etc.

I do notice however that some parts of the theme seem to be stuck without logging out and back in here in this Budgie session (e.g. I got black window borders for some apps after switching widget themes, even after changing it back to adw-gtk3)

I was really hoping for something like Vivaldi web browser. They have somehow avoided using x11 it seems.

    ruili I was really hoping for something like Vivaldi web browser. They have somehow avoided using x11 it seems.

    Not sure what you mean. Vivaldi (and/or the compositor of your desktop environment) is of course, necessarily, making use of X11 stuff when you run it in an X11 session. I'm also not sure how this relates to anything you've said previously. I thought you want to change the border colors of your whole desktop? Or are you developing an app and want to change its window border colors?

      Tried to upload a pic, didnt work. Vivladi I think uses HTML to render its window.(im a controls engineer, not programmer, limited knowledge)
      Every window opened on my desktop (accept vivaldi) has a black/grey tool bar and border. This permeates every theme. Vivladis colors are controlled from within the browser. Maybe it doesnt render a X11 window graphic is what i was thinking. it looks exactly the same on linux as it does on windows with my settings.
      As far as I can tell there doesn't seem to be an option in X11 to control those colors, or its too much trouble for anyone to bother with.
      This was just me trying to satisfy my own curiosity as to whether this was true or not.

      A little research has shown me that there is a function in X11 for border color(not sure if that includes the tool bar). It also said each new window inherits those parameters from its parent. Is a theme capable of being the parent and thus controlling those colors?
      To be clear, I am an Art Major. Black grey and white are not colors. I have had a Blue, green or teal colored desktop by choice. On all my Amiga and Windows boxes. I was surprised when i could not control this in solus. Even more surprised to find the behavior permeates all distros and themes and Apple Macs.

      Are you looking for something like this?
      This is a screenshot of Pop OS's new Cosmic Desktop. I think it's called accent colors, and you can change it. It's wayland though, not X11.