skype window does not show because it opens off screen

After a recent update of Skype it developed these symptoms: - I could see its entry in the task bar, but could not show its window by trying to maximize it - task bar window preview did show the window's thumbnail - when the window was theoretically maximized, I accidentally hovered over its area on the desktop. Mouse pointer was changing and tooltips of familiar Skype UI elements were shown. The window was there, but it was invisible. Online research suggested the window is displayed off the screen. After moving all Skype windows to 0,0 with

xdotool search --class skype windowmove %@ 0 0

Skype window was visible again. I had to use *xdotool* after every Skype start. Updating Skype from *stable* to *unstable* didn't help. My setup is Debian testing with KDE, single HiDPI monitor, nVidia GTX 980.