The Nexus 7: Google ships a tablet

"common GUI" would mean one with at least five per cent market share, which excludes KDE. I know that in the free software world there are many more options for customizing the display, and indeed I do as much as possible inside Emacs or a terminal window, with white text on black. I was lamenting that the more widespread graphical environments (MS Windows, Android, iOS, Mac OS and so on) tend not to have a simple option to change everything to white on black.