Returns TRUE if some text is selected; places the bounds
of the selection in start and end (if the selection has length 0,
then start and end are filled in with the same value).
start and end will be in ascending order. If start and end are
NULL, then they are not filled in, but the return value still indicates
whether text is selected.
Returns TRUE if some text is selected; places the bounds of the selection in start and end (if the selection has length 0, then start and end are filled in with the same value). start and end will be in ascending order. If start and end are NULL, then they are not filled in, but the return value still indicates whether text is selected.