the #GtkWidget that @area is rendering onto
the #GtkCellRenderer in @area to activate
the #GdkEvent for which cell activation should occur
the #GdkRectangle in @widget relative coordinates of @renderer for the current row.
the #GtkCellRendererState for @renderer
Return: whether cell activation was successful
3.0
This is used by #GtkCellArea subclasses when handling events to activate cells, the base #GtkCellArea class activates cells for keyboard events for free in its own GtkCellArea->activate() implementation.