[Bug 877358] Re: QtAccessibility causes crashes in several applications

[Didier Roche]

** Also affects: unity-2d (Ubuntu)
   Importance: Undecided
       Status: New

** Description changed:

  See backtraces, and possible further comments here:
  
  https://bugs.kde.org/buglist.cgi?long_desc_type=substring&long_desc=QAccessible&bug_severity=crash&bug_status=UNCONFIRMED
  
  If possible, please give instructions how to workaround it (e.g. by
  disabling QtAccessibility) until the bugs are fixed. If the crashes are
  caused by bugs in KDE applications itself, please file back bug reports
  to the KDE bug tracker.
  
  ---- SRU Info ----
  
  [Impact]
  
  QtAccessibility causes crashes in several applications when enabled.
  This affects Qt and KDE applications started on an accessibility-enabled
  desktop, be it Unity or KDE.
  
  [Development Fix]
  
  Upstream is confident QtAccessibility is stable enough in Qt 4.8 that no
  workaround will be needed in Precise.
  
  [Stable Fix]
  
  QtAccessibility does not cause Unity 2D to crash, as crashes are caused
  by widgets which are not used in Unity 2D. Since the desktop must be
  accessible, it is important to keep QtAccessibility activated for Unity
  2D, but not for other applications.
  
  Activation of QtAccessibility is controlled by the QT_ACCESSIBILITY
  environment variable.
  
  The fix consists of two steps:
  
  - Do not enable QtAccessibility if desktop accessibility is enabled.
  This is implemented in the at-spi2-core debdiff
  
  - Enable QtAccessibility at startup of Unity 2D so that the desktop
  remains accessible, but disable it before starting applications so that
  they do not suffer from the crashes.
  
  It is still possible for Qt application developers to test accessibility
  of their application by explicitly setting the QT_ACCESSIBILITY
  environment variable.
  
  [Test Case]
  
  Those crashes are difficult to reproduce, but I can reliably trigger one
  on my machine with Kopete.
  
  1. Enable accessibility
  2. Restart the session => the QT_ACCESSIBILITY environment variable should be set
  3. Start Kopete => crash
+ 4. Ensure unity-2d still have accessibility enabled
  
  [Regression Potential]
  
  This fix causes accessibility to be disabled for all Qt applications but
  Unity 2D. Users who have started to rely on QtAccessibility will not be
  able to use it anymore. We (upstream and I) believe that the current
  situation is worse and that QtAccessibility is not good enough in
  Oneiric anyway for users to rely on it yet.

** Changed in: unity-2d (Ubuntu Oneiric)
       Status: New => Confirmed

** Changed in: unity-2d (Ubuntu Precise)
       Status: New => Confirmed

** No longer affects: qt-at-spi (Ubuntu)

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https://bugs.launchpad.net/bugs/877358

Title:
  QtAccessibility causes crashes in several applications

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