void set_position ( GtkEditable* editable, gint position )
Sets the cursor position in the editable to the given value.
The cursor is displayed before the character with the given (base 0)
index in the contents of the editable. The value must be less than or
equal to the number of characters in the editable. A value of -1
indicates that the position should be set after the last character
of the editable. Note that
position is in characters, not in bytes.