Look in the widget-extras.lua file. These four lines need changed:
widget-extras.lua: background.fill = { type = “image”, filename=opt.background}
widget-extras.lua: background.fill = opt.backgroundColor
widget-extras.lua: background.fill = {1,1,1}
widget-extras.lua: background.fill = { type = “gradient”, color1={0.5, 0.5, 0.5}, color2={0, 0, 0}}
You would have to change them to not use background.fill.
Rob