If you set Breeze theme for gtk2 apps, they will have breeze color scheme, ignoring color scheme settings. Breeze-dark is the same. Reproducible: Always Steps to Reproduce: 1. Set breeze theme 2. Set custom color scheme 3. Launch any gtk2 app Actual Results: Gtk2 apps won't follow color scheme settings. Expected Results: Use color scheme I have set, as it works with oxygen-gtk I am on opensuse thumbleweed, so this should not be considered something really stable.
Unfortunately, this is going to be remain the case for some time, as we need to polish and restructure the base theme before we rewrite the color generation scripts for the GTKrc, CSS, and SVG files. That is, unless some enterprising artist and/or developer with some time on their hands wants to take on the work. Even then, GTK 3's theming machinery is being reworked so that themes don't need to be remade for each stable version of GTK any longer, so it would be wise to delay this until that work is complete to prevent duplication of effort. Until these kinks are worked out, it should be fairly straightforward for someone to modify the SVGs, SCSS, and GTKrc files to match the color scheme of their choice. I know that's no real solution, but it's probably the best we're going to get in the immediate future.
As a workaround I switched gtk theme to oxygen-gtk. Still not perfect, but much better than inconsistent colors (I use opensuse version of obsidian coast with green instead of blue, blue things look strange on suse)
We just implemented support for doing this with GTK3 apps in Bug 356006! However in the process we determined that the amount of effort require to do the same for GTH2 apps was not feasible, especially considering the benefits. Most GTK apps are now using GTK3, save for a few like GIMP and Inkscape which are actively working on porting.