Here is a video (971kb QuickTime .mov) showing a bug with envelope curvature editing.
When changing the curvature (Bézier tension) of an envelope segment with a Bézier curve
for the first time, the wrong pointer icon (i.e. the one for
moving and envelope segment, similar to the one for vertical resizing) is shown when holding its modifier key and hovering over the envelope segment. Also, the wrong description is given in the 'tooltip' and in the information display (again, it refers to moving a segment instead of changing the curvature).
Bug report thread here,
please vote if you can duplicate and care to have it fixed.