a #PangoContext, from a pangocairo font map
Callback function for rendering attributes of type %PANGO_ATTR_SHAPE, or %NULL to disable shape rendering.
User data that will be passed to @func.
Callback that will be called when the context is freed to release @data, or %NULL.
1.18
Sets callback function for context to use for rendering attributes of type %PANGO_ATTR_SHAPE. See #PangoCairoShapeRendererFunc for details.