Custom QAnimationDriver bug

I'm trying to use Qt Quick for generation image sequence for video
broadcasting and writing to the video file. To do that I need to update
Qt Quick scene animations with frame rate of the output video.

The logical way to do that is to create custom QAnimationDriver and
overload QAnimationDriver::advance and QAnimationDriver::elapsed methods.
But it does not working now. The problem is that in some cases (when a new
animation started for example) Qt updates animations using time from global
timer (QUnifiedTimer::time.elapsed()) and not from the animation driver.

Get more info from the mailing list discussion, please.
http://lists.qt-project.org/pipermail/development/2014-April/016365.html

I will provide a patch soon.