Emitted when a new extension has been added to the ExtensionSet.
It happens when a new plugin implementing the extension set's extension type is loaded.
You should connect to this signal in order to set up the extensions when they are loaded. Note that this signal is not fired for extensions coming from plugins that were already loaded when the ExtensionSet instance was created. You should set those up by yourself.
| info |
A PluginInfo. |
| exten |
A Extension. |