static var acceleration : float
Description描述
Get standard acceleration for dragging values (Read Only).
获取拖拽值的标准加速度（只读）。
Normal acceleration is 1.0. When Shift is pressed, it is 4.0; when Alt is pressed, acceleration is 0.25.
标准加速度是1.0。当按下Shift值是4.0；当按下Alt，加速度是0.25。
参见：niceMouseDelta.
