// Draw the given list of Drawables on the surface. Items should be a list of Drawables
func draw(screen *sdl.Surface, items *list.List) {
screen.FillRect(nil, uint32(0x00202020))
for cur := items.Front(); cur != nil; cur = cur.Next() {
if d, ok := cur.Value.(Drawable); ok {
d.Draw(screen)
}
}
}
// draw the marker
func (m Marker) Draw(screen *sdl.Surface) {
screen.FillRect(m.Rect(), m.Color)
}