Registers type as extension for the extension point with name extension_point_name. If type has already been registered as an extension for this extension point, the existing GIOExtension object is returned.
the name of the extension point
the GType to register as extension
the name for the extension
the priority for the extension
a GIOExtension object for GType. [transfer none]
See Implementation
Registers type as extension for the extension point with name extension_point_name. If type has already been registered as an extension for this extension point, the existing GIOExtension object is returned.