setEntryTextColumn
Sets the model column which @combo_box should use to get strings from to be @text_column.
For this column no separate class@Gtk.CellRenderer is needed.
The column @text_column in the model of @combo_box must be of type %G_TYPE_STRING.
This is only relevant if @combo_box has been created with property@Gtk.ComboBox:has-entry as true.
Parameters
textColumn
A column in @model to get the strings from for the internal entry