[Development] Removal of xlib plugin - a possible disaster.

[Rick Stockton]

http://codereview.qt-project.org/#change,20091
My negative review of the Change comes out of 3 facts:

(1) I have personally experienced the yet-to-be-documented problem, with 
both widget and declarative-based example programs, in which the GUI 
never appears: The program crashes with SIGSEGV, probably when 
attempting to assign size hints for the main Window. For me, the problem 
began occurring in February- but I wasn't doing much with Qt on XCB 
platform plugin during late January, so the problem may have been 
created/exposed at an earlier time.
In any case, it was happening 100% of the time with my Distro, Mageia-1. 
(I have new problem with Mageia-2, described as "fact #3" below.)

(2) That problem has been reported by others on IRC. I'm not capable of 
creating a "tight" search on Jira bugreports, but I didn't see a report 
for the problem. If someone can assist in that search, we'd be looking 
for xcb plugin, sigsegv crash, bug opened after the start of 2012.

(3) Wondering if my Distro was "too old", (and most of it's RPMs were 
built in April of 2011), I just upgraded to Mageia-2 "beta-2". I no 
longer get SIGSEGV, but I get a problem which _could_ be closely 
related: referencing an Undefined Symbol related to WM hints. 
https://bugreports.qt-project.org/browse/QTBUG-24835

--- comments ---
I can't think of a WORSE spectacle, for the reputation of Qt-Project, 
than the Release of an Alpha Build in which large numbers of exerpienced 
Qt users on Linux Linux _might_ be unable to use the XCB plugin and show 
a main Window, before getting some kind of 'ABEND', with _any_ of our 
own provided examples. Sending the Alpha out with xlib plugin removed 
would be like selling a car without an emergency brake: Yes, the main 
brake system is the one you should use, but if totally dies .... you 
have GOT to have another one.

With these two bugs present (i.e. SIGSEGV happening on some "older" 
Distros, and "Undefined Symbol" happening on RPMs built just 6 days 
ago), you NEED to have an alternative, EASY plugin for these people to 
use. Even at alpha.

Yes, the bugs should be documented, isolated, and fixed. But, from my 
own Test/Integration/Release career, I'd say that our choices for alpha 
are (A) leave the xlib plugin present, and maybe even make it build 
automatically on X11 systems; or (B) stop ignoring the IRC "I'm getting 
'segment fault' with an example program" postings, and POSTPONE ALPHA 
until we've got them fixed. And I'd vote for alternative A -- keep the 
alpha schedule, but provide xlib as an alternative plugin.

Just my opinion, but it's held pretty strongly. Since I have only ONE 
box, with ONE disk, I can't easily go back to mageia-1 to reproduced bug 
#1. But I'm pretty confident that some of our Qt5-Alpha-1 users will 
experience it, and their doco might help to pin it down pretty well. :)