How to change colors in GTK3

[barefootcoder]

Now that the Colors tab is gone in GTK3, how do you change the colors? I assume there's a file somewhere if nothing else, but a GUI method would be even better.

Running Mate on Sonya (18.2). Thx guys.

[aes2011]

Which gtk3 theme are you using? Some can no longer be edited simply

[barefootcoder]

Which gtk3 theme are you using? Some can no longer be edited simply

I'm currently using Mint-Merlot, which I've been dragging around with me from machine to machine ever since I discovered it like a decade ago. But I'm not sure that's relevant. I don't want to change the base theme. I want to change the current settings. So what I do is click on the "Customize" button, which makes a separate entry (called "Custom"), then I can edit that via the GUI. Except now I can't change the colors any more. So I'm assuming that "Custom" is stored somewhere, and I could edit those files without impacting the base themes, but I'm not sure where I would do that. (And, as I say, GUI would be better, IMHO ... I like doing command-line things at the command line, but doing GUI things at the CLI I find frustrating.)

[JosephM]

This really isn't possible via a GUI anymore. You pretty much have to modify the theme files.