synchronisation refresh button bug

Reproduce the bug:

Play a video file, change "advance of audio over video" setting (in "Adjustments and Effects" window) to a random value. Now click the refresh button a couple of times. The value of "advance of audio over video" gets copied to "Advance of subtitles over video" and grows with each click (by a random factor it seems).

assigned to @jbk

added Component::Interface: Qt label

Fixed... at least partly.

added Status::fixed label

closed