In addition to the title bar being dark for a open active window instead of faded, you could also try changing the color and color intensity of the taskbar to see if it helps the more frosted over icon stand out better. However, this will also change all window borders color as well. See steps 5 abd 6 in the tutorial below for more on this. Window Color and Appearance - Change
You might try the settings I use. The most frosted icon on the taskbar stands out quite clearly for me with it.
Hope this helps,