window using the given style and state and shadow type, 
leaving a gap in one side.gtkPaintBoxGap(object, window, state.type, shadow.type, area = NULL,  widget = NULL, detail = NULL, x, y, width, height, gap.side,  gap.x, gap.width)objectGtkStylewindowstate.typeshadow.typeareaNULL if the
output should not be clipped. [  allow-none  ]widgetdetailxywidthheightgap.sidegap.xgap.width