Thanks Grazie. I want the event underlying my credit roll to start fading in before the final event of my movie has finished fading out. This is just one example. I can obviously put the events on separate tracks, but the number of tracks is starting to affect the manageability of my project. A "lock fades" event switch would be just the ticket :)

I don't know how many other tracks you have, but one extra track is small price to pay for the advantage of being able to customize ovelaps.

Think of it this way: in this case you're not crossfading from one event to another. You're overlaying a credit roll on top of your video. It makes no difference whether you're starting one fade a frame before the other or if they'll both be on the screen together for hours before the video fades out. The point is that you want the two events to have disparate behavior and this is not possible with a crossfade. It can only be done of they are on separate tracks.

Crossfades on a single track in Vegas are so incredibly easy to do in part because they are somewhat limited. Then again, most of the time the behavior is exactly what people want, so this makes for a quicker and easier workflow. In other NLEs i've used a simple crossfade requires using two tracks and manually specifying the transition properties. I'll take Vegas' crossfading method any day.