All screenshots are with the following Groupy2 settings:
Place tabs above; Show all taskbar buttons; Rounded tabs; Always visible
1) Active Window; Unfocused background bar - Custom color = White; Focused background bar = Mica

Inactive Window; Unfocused background bar - Custom color = White; Focused background bar = Mica

********************************************************************************************************
2) Active Window; Unfocused background bar - Custom color = White; Focused background bar = Frame color

Inactive Window; Unfocused background bar - Custom color = White; Focused background bar = Frame Color

**********************************************************************************************************
3) Active Window; Unfocused background bar - Custom color = Dark Green; Focused background bar = Mica

Inactive Window; Unfocused background bar - Custom color = Dark Green; Focused background bar = Mica

*******************************************************************************************************
4) Active Window; Unfocused background bar - Custom color = Dark Green; Focused background bar = Frame Color

Inactive Window; Unfocused background bar - Custom color = Dark Green; Focused background bar = Frame Color

Clean install of Windows 10 - 19045.3086 with only Groupy2 General Release installed.