What, you expected it to be easy?
Is the OP looking for the first slide selected within the range, or the
lowest slide index of the selection range?
If it is the lowest slide index number, it might be worthwhile to toss the
index numbers of the range into an array and bubble sort the thing.
If it is the first slide selected, they might get better luck by trapping
slide selection change and test it against the sliderange.count. Then it is
just a matter of storing the index number whenever there is a single slide
selected (whether selecting a range with shift or control, you always have
to start with just one slide selected).
Bill