Currently icons on are only selectable in non transparent areas. This is a
usability problem both because it can make selecting certain sorts of
thumbnailed images (in particular) extremely difficult, and because it
makes the user think a little more even when they select an image with only
a few transparent areas.

Ideally, icons should be selectable only in transparent "holes" within the
icon (that is, if you have a circle with the inside of the circle
transparent, clicking in the center would select, clicking on the circle
lines themselves would select, but clicking outside the circle would NOT
select), but it would be better than the existing situation to have the
whole bounding box of the icon selectable.