Usage:
Color is system_color(Object)

Gets the color of the Object in Color .

Object can be one of the following words:

window for default window color
menu for default menu color
dialog for the dialog face color

Example:

?-
  brush(system_color(window)),
  window(_, _, win_func(_), "system_color demo", 100, 100, 200, 200).

win_func(paint) :- ellipse(50,50,150,150).