LyX crashes at startup with Qt 4.4

[bugs@…]

Hi,

if Qt 4.4 (TP1 or recent snapshots) is installed, LyX crashes at startup.
According to the trolls, this is caused by an API "misuse" that is now no
longer possible due to their making QPainter less tolerant in Qt 4.4.

Warnings and backtrace follow.

QPaintEngine::setSystemClip: Should not be changed while engine is active
QPaintEngine::setSystemClip: Should not be changed while engine is active
QWidgetPrivate::beginSharedPainter: Painter is already active

Program received signal SIGSEGV, Segmentation fault.

0xb77fec88 in QPainter::isActive () from /usr/lib/qt4/libQtGui.so.4
#1 0xb775aa55 in QWidgetPrivate::drawWidget () from /usr/lib/qt4/libQtGui.so.4
#2 0xb775b8b7 in QWidgetPrivate::paintSiblingsRecursive ()
from /usr/lib/qt4/libQtGui.so.4
#3 0xb775b7a4 in QWidgetPrivate::paintSiblingsRecursive ()
from /usr/lib/qt4/libQtGui.so.4
#4 0xb775b7a4 in QWidgetPrivate::paintSiblingsRecursive ()
from /usr/lib/qt4/libQtGui.so.4
#5 0xb775b7a4 in QWidgetPrivate::paintSiblingsRecursive ()
from /usr/lib/qt4/libQtGui.so.4
#6 0xb775b7a4 in QWidgetPrivate::paintSiblingsRecursive ()
from /usr/lib/qt4/libQtGui.so.4
#7 0xb775aba0 in QWidgetPrivate::drawWidget () from /usr/lib/qt4/libQtGui.so.4
#8 0xb78c6fc2 in ?? () from /usr/lib/qt4/libQtGui.so.4
#9 0xb78c7ea8 in ?? () from /usr/lib/qt4/libQtGui.so.4
#10 0xb77609e0 in QWidget::event () from /usr/lib/qt4/libQtGui.so.4
#11 0xb7adeb8f in QMainWindow::event () from /usr/lib/qt4/libQtGui.so.4
#12 0x084555ca in ?? ()
#13 0xb770344c in QApplicationPrivate::notify_helper ()
from /usr/lib/qt4/libQtGui.so.4
#14 0xb77058ec in QApplication::notify () from /usr/lib/qt4/libQtGui.so.4
#15 0x0844c04f in ?? ()
#16 0xb73dc027 in QCoreApplication::notifyInternal ()
from /usr/lib/qt4/libQtCore.so.4
#17 0xb73dd3f7 in QCoreApplicationPrivate::sendPostedEvents ()
from /usr/lib/qt4/libQtCore.so.4
#18 0xb73dd6cd in QCoreApplication::sendPostedEvents ()
from /usr/lib/qt4/libQtCore.so.4
#19 0xb779a4c8 in ?? () from /usr/lib/qt4/libQtGui.so.4
#20 0xb73db192 in QEventLoop::processEvents () from /usr/lib/qt4/libQtCore.so.4
#21 0xb73db2c0 in QEventLoop::exec () from /usr/lib/qt4/libQtCore.so.4
#22 0xb73dd78b in QCoreApplication::exec () from /usr/lib/qt4/libQtCore.so.4
#23 0xb7702e27 in QApplication::exec () from /usr/lib/qt4/libQtGui.so.4
#24 0x08193062 in ?? ()
#25 0x08069172 in ?? ()
#26 0xb6e293ec in libc_start_main () from /lib/libc.so.6
#27 0x08069001 in ?? ()

Thanks,
~ Manuel aka Sput

[Juergen Spitzmueller]

Hm. Abdel, could you take a look?

[younes]

A more detailed description of the API misuse would be nice as the backtrace is
not helpful (nothing from LyX source code in there).
I don't have the time to follow Qt snapshot so I think I'll wait for the 4.4
release.

[ps@…]

first of all lyx is not compilable under qt 4.4, it may be that after linking
against qt 4.4 this bug disappear.

[Uwe Stöhr]

LyX 1.5 supports Qt 4.1 - 4.3. We will support Qt 4.4 when it is officially
released by Trolltech. For now the bug is invalid.

[goodrich@…]

Please consider reopening this bug. Although qt 4.4 is not released yet, the qt
4.4 RC is in Debian unstable and is already causing headaches for people

​http://www.mail-archive.com/lyx-users@lists.lyx.org/msg63985.html
​http://www.mail-archive.com/lyx-devel@lists.lyx.org/msg138750.html
​http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=475523
​http://sidux.com/PNphpBB2-viewtopic-t-9925.html

I believe qt 4.4 may also be included in Kubuntu Hardy Heron.

Thank you,
Ben

[younes]

Reopening bug. Qt4.4 is closed to be released and is already distributed at a
few place. In addition fixing it was easy :-)

Waiting for Juergen approval.

[younes]

fix

[Juergen Spitzmueller]

Abdel, please commit if it fixes this bug.
I agree that we should support qt4.4.

[younes]

I comitted a minimal version of it. The other changes were not necessary.