In beta version 2.52.1024 (201002251216) clicking on the grey area surrounding the close button (meaning the whole area of the same "level" as indicated by the red line in the image below) results in several pop-ups (intended for the development-area, but not for public versions).
This is valid for any preferences-window. Contents of pop-up message depends on window and on the position where clicking is done. I copied some pop-ups in the image by way of example:
(Note: also added to main=initial post of this thread; fixes will be mentioned in main post)