You can invoke it by clicking on a really small ( may be, a 1 * 1 px ) button on the About Flash splash screen. I'm not gonna spoil the party by exposing where the button is, its fun clicking all over the dialog, for sometime :)
When Flash CS3 Professional was released last year, I did a similar post. When I installed CS4 today, first thing that came to mind was to go find the easter egg. And I got lucky in a few clicks. Lets see how many releases I can keep doing this ;)
M Williams passed away a lil while ago. This picture will carry his memories as long as Flash CS4 lives!
And Robert Penner. the easing hero :)
I decided to stop at 2 screenshots, but this pic of Sean is too funny to let go!
Ok, I can't contain any longer, time to go try out the new features!
