Issue 71319

This problem only occurs intermittently, and I have no clue why the expected
behaviour works sometimes and not others; I can't find a distinct pattern,
although I haven't looked at it exhaustively.

To recreate this problem:

1. Open or create a presentation with at least five slides (enough so that they
don't all show up on the slidebar - try 12).
2. Click on one slide, then scroll down/up (this behaviour tends to happen more
frequenly when scrolling with the scroll bar), press and hold the shift key,
then click another. Sometimes it will select the entire range of slides, but
sometimes it will only select the most recently-selected slide.
3. Click on another slide, and keep selecting multiple slides in this way; it
doesn't necessarily have to be when you scroll. 

Again, I'm not quite sure what the difference is when it (the preferred
behaviour) does and doesn't work. Sometimes the slides quickly all highlight,
but immediately deselect, except for the current one.

- RG>