Currently, keyframes 
- are contained "inside" the boundaries of the clips (ie: they can't "bleed" over the border and outside the clip's bounding box)
- are shown under the trimming handles

This is problematic because it's basically impossible to manipulate the first and last keyframe.

A potential way to work around this would be to layer the curves+keyframes "on top" of trimming handles, and making the keyframes/curves' hitbox prioritized over the trimming handle's hitbox (since it's large enough anyway). Thus if we can see and click the keyframe at the end of a clip even though the trimming handle is shown under, then we can do manipulations such as fades much more easily (at least until we have "real" transitions and bug #579230 cornered).