xlib plugin is dead (for Qt5)

[Fredrik Höglund]

On Wednesday 28 March 2012, Rick Stockton wrote:
> In a merge earlier today, Qt-Project removed the xlib support code form 
> Qt5. (I was not the Approver, but I did vote "+1" on the change). For 
> X11 environments, xcb will be it's replacement. Wayland is also a 
> "primary" platform, but IMO not completely ready for prime-time use as a 
> Qt back-end. (QT requires an SHA1 level of Wayland which is somewhat 
> old, slightly buggy, slightly less efficient than current Wayland Git, 
> which also adds a few new features over the level now required by 
> Qt5-Wayland.)

This move has been expected for some time, so we have already started
porting the Xlib code in KDE to xcb.  See the email with the subject
"Porting the NETWM classes to xcb" I posted about a week ago.
 
> xcb also has some performance enhancements init's current Git version, 
> compared to the recent official Releases (1.8.0 and 1.8.1). If you build 
> Qt against a Released Version, (e.g. 1.8.1), Qt "configure" will include 
> a line in it's Build Summary, saying that "xcb support is limited (old 
> version)." This message is with respect to those recent changes, which 
> allow for more efficient painting.

The performance improvement you're referring to is in 1.8.0.
If the configure test fails to detect that, there's something wrong
with the test.

Fredrik