The "row-activated" signal is emitted when the method row_activated is called, when the user double clicks a treeview row with the "activate-on-single-click" property set to false, or when the user single clicks a row when the "activate-on-single-click" property set to true.
It is also emitted when a non-editable row is selected and one of the keys: Space, Shift+Space, Return or Enter is pressed.
For selection handling refer to the tree widget conceptual overview as well as TreeSelection.
the TreePath for the activated row
the TreeViewColumn in which the activation occurred