If one has a selected slide, holds down shift, and clicks other slides - a range selection is effected. But if in the same situation, one mistakenly clicks an area of the slide pane which is not associated wit a given slide (e.g. too far to the side) - then instead of not doing anything, or resetting the selection to just the single initial slide - the selection changes to the earliest slide in the presentation that is in the current range; and the range is no longer updated by mouse clicks on slides.

I believe this is unintuitive and undesirable behavior and should be changed to one of the two options I mentioned earlier.