Version:           2.2 (using KDE 4.5.2) 
OS:                Linux

The kpresenter document panel, which list the slide, currently requires using ctrl+click to select multiple slides.  However, many applications in KDE also have +/- buttons that appear when you mouse over an item to allow you to select or deselect multiple items without using the keyboard.  Applications that do this include dolphin, gwenview, digikam, and plasma folderview.  This is a great feature and very useful for easily selecting items.

These buttons I think are the bare minimum, but applications like gwenview and digikam offer additional buttons as well.  Possibilities for additional buttons include an "add new layer" button, "duplicate slide" button, a "delete slide" button (with confirmation, of course), show/hide slide in slideshow, and a button that pops up a list of slide templates to let you change the template of the slide.

If you hover your mouse between two slides for a moment, a button could also appear to let you make a new slide there.

I think these sorts of buttons could make working with slides more convenient than in any other presentation program out there.

Reproducible: Didn't try