A GtkPopover to select Port's.
- Port* port
- The owner Port.
- Track* selected_track
- Track selected in the Track treeview.
- Plugin* selected_plugin
- Plugin selected in the Plugin treeview.
- int track_ports_selected
- Used if selected_plugin is NULL.
- bool setup
- Whether already set up (to avoid re-adding existing widgets).
Plugin selected in the Plugin treeview.
If this is NULL, see track_ports_selected.
Used if selected_plugin is NULL.
If this is 1, the track ports are selected, otherwise if this is 0 then nothing is selected in the Plugin treeview.