ExtensionSet

Create a new ExtensionSet for the exten_type extension type.

At any moment, the ExtensionSet will contain an extension instance for each loaded plugin which implements the exten_type extension type. It does so by connecting to the relevant signals from [class@Engine].

The property values passed to ExtensionSet will be used for the construction of new extension instances.

If engine is null, then the default engine will be used.

See [method@Engine.create_extension] for more information.

Parameters:

engine	A Engine, or null.
exten_type	the extension Type.
first_property	the name of the first property.
...	the value of the first property, followed optionally by more name/value pairs, followed by null.

Returns:

a new instance of ExtensionSet.