(gobject:define-genum "GtkCellRendererMode" cell-renderer-mode
  (:export t
   :type-initializer "gtk_cell_renderer_mode_get_type")
  (:inert 0)
  (:activatable 1)
  (:editable 2))  

:inert

The cell is just for display and cannot be interacted with. Note that this does not mean that the row being drawn cannot be selected - just that a particular element of it cannot be individually modified.

:activatable

The cell can be clicked.

:editable

The cell can be edited or otherwise modified.