Reply to @Paul+Baranowski: 1.9.5 this bug is only reproductable when using scroll with 2 fingers (when page content is dragged out of the view port a bit). This is not reproductable when scrolling with a scroll on a mouse.
Reply to @Martin+Konecny: I've tested the ipad's safari more carefully. The similar thing happening with it sometimes. Ive noticed it when changing orientation with show/add content modal dialog opened. I guess this is a drawback of dynamically adjusting the page size and header location.
By the way, the drag-drop also doesn't work on ipad too. And if i'm able to add items to playlist using context menu, i'm still unable to add content to the show. The context doesn't work there.