I am using Gnome 3.12.2
This is a screenshot taken when I press Prt Scr (I have a dual screen. Chrome is maximised).
This is one is taken when I do Alt+Shift+4 (My shortcut to take an area screenshot).
This is what happenes when I do Super+Print
It varies though. Sometimes it it completely white or black or transparent. Google chrome and terminal are completely black, Inkscape is yellow, and . The white space on that one atually has random transparent marks on it:
(Screenshot of image viewer display)
I also have a shortcut Ctrl+Alt+Prt Scr to take a screenshot of a window and copy it to the clipboard.
That produced the same as above.
Finally, a screenshot of my list of Screenshot shortcuts, taken with area shot.
NVIDIA legacy binary driver - version 304.117 from nvidia-304 (proprietary)