Created attachment 226114 [details]
Check out the 'Interactive DnD Mode' tab

I expect the foreground 'color' to change to :active when I click on a new tab. The background style changes but the foreground remains the same.

Set up:
---
.notebook tab {
        background-image: -gtk-gradient (linear,
                0 0, 0 1,
                color-stop(0, shade(#aaa, 0.6)),
                color-stop(0.1, alpha(mix(#aaa, #fff, 0.7), 0.1)),
                color-stop(0.4, mix(#000, @transparent, 0.7)),
                color-stop(0.9, @transparent));
        border-color: alpha (mix (@bg_color, #777, 0.3), 0.4);
        padding: 2px;
        color: shade (@theme_fg_color, 0.5);
}
 
.notebook tab:active {
        background-image: -gtk-gradient (linear,
                0 0, 0 1,
                color-stop(0, shade(#ccc, 0.6)),
                color-stop(0.1, alpha(mix(#ccc, #fff, 0.7), 0.4)),
                color-stop(0.4, mix(#ccc, @transparent, 0.8)),
                color-stop(0.9, @transparent));
        border-color: alpha (mix (shade (@bg_color, 1.4), #777, 0.5), 0.3);
        color: @theme_fg_color;
}
---

Results:
see attachment - the Code Demos window shows the initial state and the Tool Palette window demonstrates the problem.