Ah sorry, it was about 200 x 200 pixels.
It was the floating Note, activated from the main menu\Notes.
But I don't seem to be able to reproduce it again. I'll be back if I can.
It appeared when viewing and then docking the window. I think I first docked the Note pane to the bottom of the right column, and then the grey area covered the whole thing, and so I moved it to the bottom of the main viewing area, but the gray all-covering area was still stuck to the Note pane.
I (thinkI) have a screenshot (somewhere in a temp folder) from when it occured, but how do I upload that?
Regards,
// Rolf Lampa