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I have Ubuntu 18.04 LTS 64bit running on a Toshiba laptop.
About a week ago, some applications, e.g. Firefox, Aisle Riot Solitaire, KPatience, XTide tide predictor etc. when launched have the top left corner of the window too far up and left, partly hiding them under the quick launch icons on the left of the screen (i.e. under the Ubuntu Dock).
This makes them difficult to use and the window can only be closed by using the 'Quit' option from the quick launch icon on the left of the screen. Other applications such as Libre Office, OpenCPN, GNU Image Manipulation Program etc behave normally.
What is happening here and how to fix it?