Colourchange in the BluePrint.xaml file of the skin template

[Mirasol]

Hello,
so far I know how to work on the colour changes in the BluePrint.xaml file. I already was able to change the colour for the title bar.in an active window (see 1st Pic)

But where can I change the chartframe colour, for an active window, so that it looks like in pic 2? In which line of the BluePrint.xaml the chart border frame is mentioned?

Thanks a lot for help.

Regards André