The bottom windows all seem to be hard-coded with a background color of white, with the exception of the 'Reports" window, which seems to be using the Windows Control Panel color (thanks, "Reports" developer).
I would prefer for them to use the Windows Control Panel window background color. At one point in time this was standard behavior for Windows applications, but these days I've noticed most developers just code to white or "no color", which results in some oogly web pages for those of us using a non-white Control Panel background color (the graphics with white, non-transparent backgrounds form disjoint shapes around the areas with the Control Panel Color).
Please fix TheBrain to use the Windows Control panel background color, or allow a user-selectable background color. If the color is made selectable, one of the choices should be the Windows Control Panel background color(!)
P.S. I typically use "money green" (RGB 192,220,192). This was one of the original Windows 3.0 16 standard colors, and I use it on most of my systems. I find white to be too bright and fatiguing (try it!)