Change the fading and showing curve effect when hovering the bfb

I think the key is a "flash" or similarly visible transition from
"coming" to "arrived". John Lea will work on this and provide guidance.

Mark

just a few comments because i was rather confused when i first had this feature land in trunk;

animation alpha doesn't seem to go from 0.0 -> 1.0, it just "appears" suddenly quite opaque which left me confused as to why that was happening.

quite a few times this morning i have left my mouse cursor up on the top left of the screen, i think because i have a plugged in mouse and it pulls to the top left sometimes, anyway i'll return to my machine to find a semi-transparent launcher just sitting on my desktop which looks weird, i had no idea why that was there at the time. maybe a fade out if the cursor doesn't move for some amount of time?

when i first figured what was going on, and i "locked" the launcher, it didn't feel locked, it felt like it was stuck, almost wanted to file a bug because as i moved the mouse after it "locked", it no longer faded

@Mark: I've quickly implemented a better curve to show the launcher and I think we get the "flash" by a very quick (4/5 frames) state changes from a 75% of opacity to 100%. I think that's the desired effect. Should be available in tomorrow daily build.

After spending some time seeing when this is 'successful' vs. not (3 distinct methods 'work' with all autohide modes), it seems issue. if any, is the dimming of the launcher icons. The launcher is only active when the icons are at their brightest, ie. hitting the right spot and not unsetting on exiting into the launcher.
So the changes described will likely make this easier to do, and recognize the action in the first place.

Though reading thru the usability report from Nov., it wouldn't surprise me if many users are confused by the dual purpose of that area, things that are hidden are just that to many. There is nothing visible to suggest using the left side of the box vs. the icon in the middle which produces a dimmed launcher.