I'd suggest to turn line 367 in FontManager.cpp
CurFont.Texture.SetPixel(x + Left, y + Top, Color(Pixels[x], Pixels[x], Pixels[x], Pixels[x]));
into
CurFont.Texture.SetPixel(x + Left, y + Top, Color(255, 255, 255, Pixels[x]));
So text should be more readable on colored text/background.