Toplevel for embedding into other processes

Together with Socket, Plug provides the ability to embed widgets from one process into another process in a fashion that is transparent to the user. One process creates a Socket widget and, passes the ID of that widgets window to the other process, which then creates a Plug with that window ID. Any widgets contained in the Plug then will appear inside the first applications window.

| GObject
| +----Object
| +----Widget
| +----Container
| +----Bin
| +----Window
| +----Plug