This signal is a sign for the cell renderer to update its
value from the cell_editable.
Implementations of GtkCellEditable are responsible for
emitting this signal when they are done editing, e.g.
GtkEntry is emitting it when the user presses Enter.
gtk_cell_editable_editing_done() is a convenience method
for emitting GtkCellEditable::editing-done.
This signal is a sign for the cell renderer to update its value from the cell_editable. Implementations of GtkCellEditable are responsible for emitting this signal when they are done editing, e.g. GtkEntry is emitting it when the user presses Enter. gtk_cell_editable_editing_done() is a convenience method for emitting GtkCellEditable::editing-done.