As a workaround, I commented out everything but the last line of qjackctlClientListView::eventFilter () in qjackctlConnect.cpp, and to my surprise I get a reasonable tooltip when hovering over the port lists in the Connect window (and no more segfaults). 


----- Original Message ----
From: Ken Ellinwood <>
Sent: Thursday, July 12, 2007 1:32:31 PM
Subject: [qjackctl-devel] Seqfault in 0.3.0 related to port tooltips in connection window


I've recently compiled/installed jack version 0.107.2  from svn version 1050.  I then got the qjackctl-0.3.0 code and compiled/installed that.   qjackctl is segfaulting when I hover the mouse over any of the ports listed in the connect window
(any/all ports under audio/midi/alsa, readable or writable) .  The tooltips are working fine in the other windows (main, setup, patchbay, about) and in the connect window the tooltips do appear for the port list header and the 'Refresh' button without causing a crash.   I tried to debug this problem a bit further, but my experience with c++/QT is lacking so the best I can do is provide a stack trace.


ken@rockfish:~/qjackctl-0.3.0$ gdb ./qjackctl

GNU gdb 6.4.90-debian
Copyright (C) 2006 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i486-linux-gnu"...Using host libthread_db library "/lib/i686/cmov/".

(gdb) run
Starting program: /home/ken/qjackctl-0.3.0/qjackctl
[Thread debugging using libthread_db enabled]
[New Thread -1225864992 (LWP 8959)]
Qt: gdb: -nograb added to command-line options.
         Use the -dograb option to enforce grabbing.
Warning: no locale found: /usr/share/locale/qjackctl_en_US.qm
[New Thread -1231651952 (LWP 8965)]
[New Thread -1242375280 (LWP 8974)]

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread -1225864992 (LWP 8959)]
0xb7740ba2 in operator new () from /usr/lib/
(gdb) bt
#0  0xb7740ba2 in operator new () from /usr/lib/
#1  0xb774dc0d in QApplicationPrivate::QApplicationPrivate () from /usr/lib/
#2  0xb778aff1 in QWidget::window () from /usr/lib/
#3  0xb7781b65 in QToolTip::showText () from /usr/lib/
#4  0xb778166f in QToolTip::showText () from /usr/lib/
#5  0xb77817ad in QToolTip::showText () from /usr/lib/
#6  0x0805bc16 in qjackctlClientListView::eventFilter (this=0x81c0f20, pObject=0x8180590, pEvent=0xbfde5d00) at src/qjackctlConnect.cpp:808
#7  0xb77443c0 in QApplicationPrivate::notify_helper () from /usr/lib/
#8  0xb7745d5c in QApplication::notify () from /usr/lib/
#9  0xb758a55a in QCoreApplication::notifyInternal () from /usr/lib/
#10 0xb7741177 in operator new () from /usr/lib/
#11 0xb77481ac in QApplication::event () from /usr/lib/
#12 0xb7744445 in QApplicationPrivate::notify_helper () from /usr/lib/
#13 0xb774475e in QApplication::notify () from /usr/lib/
#14 0xb758a55a in QCoreApplication::notifyInternal () from /usr/lib/
#15 0xb758d923 in QCoreApplicationPrivate::appName () from /usr/lib/
#16 0xb75b68c9 in QEventDispatcherUNIX::registerTimer () from /usr/lib/
#17 0xb75b3848 in QEventDispatcherGlib::~QEventDispatcherGlib () from /usr/lib/
#18 0xb708c952 in g_main_context_dispatch () from /usr/lib/
#19 0xb708f91f in g_main_context_check () from /usr/lib/
#20 0xb708fe85 in g_main_context_iteration () from /usr/lib/
#21 0xb75b31f0 in QEventDispatcherGlib::processEvents () from /usr/lib/
#22 0xb77db188 in QX11Info::copyX11Data () from /usr/lib/
#23 0xb75874e2 in QEventLoop::processEvents () from /usr/lib/
#24 0xb7587664 in QEventLoop::exec () from /usr/lib/
#25 0xb758aca7 in QCoreApplication::exec () from /usr/lib/
#26 0xb7743fc8 in QApplication::exec () from /usr/lib/
#27 0x08057c56 in main (argc=Cannot access memory at address 0x0
) at src/main.cpp:90

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