focus
This should be called by the @area’s owning layout widget when focus is to be passed to @area, or moved within @area for a given @direction and row data.
Implementing GtkCellArea
classes should implement this method to receive and navigate focus in its own way particular to how it lays out cells.
Return
true if focus remains inside @area as a result of this call.
Parameters
direction
the GtkDirectionType