Can you help me with panel thumbnails preview? I have glitches on preview.
Same issue for me, sometimes until some time running. I think is a bug for a relative new feature, hope probably solved soon.
Please file a bug report on this. Steps to do so are here.
This would be filled against mate-panel , in this case you can do an:
Press Alt+F2 and type ubuntu-bug mate-panel
Please provide as much details as possible.