gnome-panel with Radiance is missing active window distinction

[Christophe]

gnome-panel with the Radiance theme is missing any active window distinction.

Ubuntu 16.04
Gnome classic

Package: light-themes
Version: 14.04+16.04.20160415-0ubuntu1

Suggested fix:

In file:
Radiance/gtk-3.0/apps/gnome-panel.css

Add:

PanelApplet .button:checked {
    background-image: -gtk-gradient (linear, left top, left bottom,
                                     from (shade (@dark_bg_color, 0.8)),
                                     to (shade (@dark_bg_color, 1.0)));
}

PanelApplet .button:checked:prelight {
    background-image: -gtk-gradient (linear, left top, left bottom,
                                     from (shade (@dark_bg_color, 1.0)),
                                     to (shade (@dark_bg_color, 1.1)));
}

PanelApplet .button:checked:prelight:active {
    border-image: none;
    background-image: -gtk-gradient (linear, left top, left bottom,
                                     from (shade (@dark_bg_color, 0.6)),
                                     to (shade (@dark_bg_color, 0.7)));
    border-color: shade (@dark_bg_color, 0.8);
}