System Color file

In config.pro add a line:

system_colors_file

Give it the value               X:\<directory>\default.scl

Where X:\<directory> is the place you want to put a default color file. 

The default.scl can have any name with the extension .scl.

Now create a text file with the following in it:

SYSTEM_BACKGROUND_COLOR 0.000000 0.000000 31.764706

BLENDED_BACKGROUND no

SYSTEM_TOP_BLENDING_COLOR 0.000000 36.470588 60.784314

SYSTEM_BOTTOM_BLENDING_COLOR 0.000000 6.666667 19.607843

Name it default.scl or the name you chose.