Set the selection between the anchor point and index: if index is before the anchor point, the selection runs from index up to but not including the anchor; if index is after it, from the anchor up to but not including index; if they coincide, nothing happens. The anchor point is the one set by the most recent selection_from() or selection_adjust() call. If there is no selection in the entry, a new one is created using the most recent anchor point. select_to() is an alias of selection_to().