[Bug]: Ribbon backcolours to match theme panel colour(s)

[Smurf-IV]

Using today's alpha and the Ribbon Controls demo (.net core)

Expected:

Actual:

etc.

[PWagner1]

This will likely fix #1564

[PWagner1]

Appears to be controlled by

Color.FromArgb(190, 190, 190), // RibbonGroupsArea1
            Color.FromArgb(210, 210, 210), // RibbonGroupsArea2
            Color.FromArgb(213, 219, 231), // RibbonGroupsArea3
            Color.FromArgb(249, 249, 249), // RibbonGroupsArea4
            Color.FromArgb(243, 245, 249), // RibbonGroupsArea5

[PWagner1]

Ok, so the back colour is controlled by these values

[giduac]

@Wagnerp & @Smurf-IV,

The Visual Studio and 365 varieties have the same background color as the Panel.
But for my taste it also looks good when the Ribbon contrasts against the Panel.
I think that should be the choice of the user and be left as it is...