[Impress] Slide sidebar always behaves as if pointer is clicked

When I’m scrolling through my slides, individual slides are selected and moved as if the pointer is continually being held down. A single click on a slide to select it (for the main view) and then a scroll will select multiple slides. Clicking again to unselect (the now selected slides) will now try to drag the newly select slide wherever you scroll next.

This makes it very difficult to work with more than 4-5 slides.

This is still an issue Sep '18, and to clarify this is using a trackpad.