How do I change background color in X11

Is it possible to change default background color of windows directly in X11? If yes, how?

Entering 'linux change background color in X11' in your preferred search engine should yield hundreds of links. Most are specific to either the Linux distro or the desktop being used, so we can't help you pick the correct answer, since you didn't give us any of that information.

Please read the links about Questions in my signature.

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