1) Start the Nevron UI Examples program

2) Press the Launch Example button on the Docking Panels > Mdi Children Custom Frames panel

3) While leaving this launched example up go back to the examples program and select Edit>Skinning>Office 2007 Blue and notice the Mdi sample changes to reflect this blue skin in many ways (though not its frame)

4) Now select Edit>Skinning>Mac OS.  Notice how the Mdi sample changes to reflect this but the sample keeps the light blue background for the Mdi area.  This happens on the other skins too except the Office 2007 Black.

I'm using the 11.1.17.12 version.  I'm seeing this color problem in my code too.