This is simple as3 class. You can add "MouseObject.as" to your "Classes" dir and use "main.as" in your project.
You can change "shar" object in library to any other images or animation for leafs.
Setting MouseObject.as:
private var speedY:Number = 4;//speed ОY
private var speedX:Number = 7;//speed ОX
private var scaleMin:Number = 0.1;//min size of object
private var scaleMax:Number = 1;//max size of object
private var alfa:Number = 0.02;//speed of fadeout
obj.gotoAndStop(Math.round(Math.random()*5+1));//random frame(object variation)
Setting Main.as:
private var density:Number = 2;//time interval of creating objects