I would like to know whether it is possible to control the amount of translucency in the so-called vibrancy effect introduced recently by Yosemite, which can be implemented in an Objective-C app by employing the NSVisualEffectView class.
Here is an example to be more specific. Consider the translucent effect which is shown by Yosemite OS X when the volume level is changed:

The vibrancy is much stronger than what one obtains by using a simple NSVisualEffectView (shown in the following image)

If we compare the two images — please, ignore the different form of the speakers but focus on the background — we see that the amount of vibrancy (the strength in the Gaussian blurring effect) is much stronger in the Yosemite OS X volume window instead of my app using NSVisualEffectView. How can one obtain that?