gsk:renderer-render (renderer root &optional region)

renderer -- a gsk:renderer instance
root -- a gsk:render-node instance
region -- an optional cairo:context-t instance with the region that must be redrawn or the default nil value for the whole window

Renders the scene graph, described by a tree of gsk:render-node instances, ensuring that the given region gets redrawn. Renderers must ensure that changes of the contents given by the root node as well as the area given by region are redrawn. They are however free to not redraw any pixel outside of region if they can guarantee that it did not change.

The renderer will acquire a reference on the gsk:render-node tree while the rendering is in progress.