code: func (v *ViewPort) GetPhysical() (int, int, int, int) {
  	return v.physx, v.physy, v.physx + v.width - 1, v.physy + v.height - 1
  }
docs: // GetPhysical returns the upper left and lower right coordinates of the visible
  // content in the coordinate space of the parent.  This is may be the physical
  // coordinates of the screen, if the screen is the view's parent.