The characters that are retrieved are those characters at positions
from start_pos up to, but not including end_pos. If end_pos is negative,
then the characters retrieved are those characters from start_pos to
the end of the text.
Note that positions are specified in characters, not bytes.
a pointer to the contents of the widget as a
string. This string is allocated by the gtk.editable.Editable implementation
and should be freed by the caller.
Retrieves a sequence of characters.
The characters that are retrieved are those characters at positions from start_pos up to, but not including end_pos. If end_pos is negative, then the characters retrieved are those characters from start_pos to the end of the text.
Note that positions are specified in characters, not bytes.