#1 Freeze happens when a window is dragged to the top #2 Freeze happens when a window is dragged to edges to attempt tiling. Note: #1 Proprietary nVidia GPU drivers were used. #2 This issue does not happen when using Intel Integrated Graphics. #3 There is a work around to prevent freezing - by disabling tiling features, under Desktop Behavior -- Screen Edges -- Window Management. Description of freezing: #1 The entire screen freezes, i.e all animations stop. #2 The cursor can move, but all clicks/right-clicks do not work. #3 Keyboard shortcuts do not work either, though after the OS stopped freezing, the shortcuts did work - hence the multiple Konsole windows you saw on my desktop. #4 When the freeze stops - system continues as usual with no issues. OS: Kubuntu 19.04 GPUs: nVidia GeForce 940m & Intel HD 5500 Graphics.