icon of the active program

[Golddouble]

MX Linux 19 (Debian)
Xfce

I know, it's only beta state until now.

I use this theme:

The icon of the active program is marked very pale. It's only like a very faint shadow. I can barely see it. And I have not found an option in this theme to change this. Do I miss anything.

Better would be a yellowish background of the aktive firefox. Or light green. So that we can see it better.

Or it should be darker on light backgrounds, but brighter on dark backgrounds.
Actually I will change to a dark background. I have only tried out a white background, to see whether the active icon is marked at all.

[Golddouble]

Here the same with dark background.

Firefox is active. But it can't be seen:

[xuzhen]

The color of Active window (or Aktive Fenster in your screenshot) is for the window list popup, not for the icon in dock.
There is currently no way to set the highlight color of the active window in the dock for the Colors theme.

[xuzhen]

You could modify the theme file, change active.png in the pixmaps directory to the color you want.
Here is an example with yellow background. Put Colors.tar.gz into ~/.local/share/dockbarx/themes/