This helper shall be used by classes implementing the gstinterfaces.VideoOverlay
interface that want the render rectangle to be controllable using
properties. This helper will parse and set the render rectangle calling
VideoOverlay.setRenderRectangle.
This helper shall be used by classes implementing the gstinterfaces.VideoOverlay interface that want the render rectangle to be controllable using properties. This helper will parse and set the render rectangle calling VideoOverlay.setRenderRectangle.