Creates a new plugin manager for the given #PeasEngine.
If @engine is %NULL, then the default engine will be used.
A #PeasEngine, or %NULL.
Return: the new #PeasGtkPluginManager.
ConstructionException GTK+ fails to create the object.
See Implementation
Creates a new plugin manager for the given #PeasEngine.
If @engine is %NULL, then the default engine will be used.