early part of the 2000s, however, it was overhauled to resolve a number of problems that had surfaced over the years, including a "flawed" font architecture, a 2D graphics system "which had always been intended to be augmented and/or replaced", and latency issues. X11R6.8 came out in September 2004. It added significant new features, including preliminary support for translucent windows and other sophisticated visual effects, screen magnifiers and thumbnailers, and facilities to integrate with 3D immersive display systems such as Sun's Project Looking Glass and the Croquet project. External applications called compositing window managers provide policy for the visual appearance. On 21 December 2005, X.Org released X11R6.9, the monolithic source tree for legacy users, and X11R7.0, the same source code separated into independent modules, each maintainable in separate projects. The Foundation released X11R7.1 on 22 May 2006, about four months after 7.0, with considerable feature improvements. XFree86 development continued for a few more years, 4.8.0 being released on 15 December 2008. Nomenclature The proper names for the system are listed in the manual page as X; X Window System; X Version 11; X Window System, Version 11; or X11. The term "X-Windows" (in the manner of the subsequently released "Microsoft Windows") is not officially endorsedwith X Consortium release manager Matt Landau stating in 1993, "There is no such thing as 'X Windows' or 'X Window', despite the repeated misuse of the forms by the trade rags"though it has been in common informal use since early in the history of X and has been used deliberately for provocative effect, for example in the Unix-Haters Handbook. Key terms The X Window System has nuanced usage of a number of terms when compared to common usage, particularly "display" and "screen", a subset of which is given here for convenience: device A graphics device such as a computer graphics card or a computer motherboard's integrated graphics chipset. monitor A physical device such as a CRT or a flat screen computer display. screen An area into which graphics may be rendered, either through software alone into system memory as with VNC, or within a graphics device, some of which can render into more than one screen simultaneously, either viewable simultaneously or interchangeably. Interchangeable screens are often set up to be notionally left and right from one another, flipping from one to the next as the mouse pointer reaches the edge of the monitor. virtual screen