var currentX:Number = bg_mc._x;
var leftnewX:Number = (bg_mc._x + 50);
var rightnewX:Number = (bg_mc._x - 50);
var friction:Number = 0.5;

left_btn.onRelease=function()
{
	leftnewX = (bg_mc._x + 50);
	while(leftnewX != currentX){
		bg_mc._x += ((leftnewX - currentX)*friction);
		currentX = bg_mc._x;
	}
}