I also have the exact same problem!!!
Do you guys also have Nvidia/Intel Optimus enabled graphic card?
According to this link, it might be the source of the problem: http://www.nex.be/press/2014/04/04/vlc- ... -solution/
Recently I updated from 8.6 to 9.8 and I was impressed by the new interface. One thing I noticed was the the popup bar in full screen mode was not as big as in maximized windows. This makes it difficult to seek. I would request that the popup bar be as wide as the screen in the full screen mode. all...