I have just realized I didn't atach all the threads' backtrace, so I am submitting them just in case.
(gdb) thread apply all bt Thread 13 (Thread 0x7fffdf0ec700 (LWP 32017)): #0 0x00007ffff4cc9e33 in poll () from /lib/x86_64-linux-gnu/libc.so.6 #1 0x00007ffff40ea624 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #2 0x00007ffff40ea744 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #3 0x00007ffff5aea296 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #4 0x00007ffff5aba8af in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #5 0x00007ffff5abab38 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #6 0x00007ffff59bdd70 in QThread::exec() () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #7 0x00007ffff5a9b1bf in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #8 0x00007ffff59c0d0b in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #9 0x00007ffff5729b50 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #10 0x00007ffff4cd4a7d in clone () from /lib/x86_64-linux-gnu/libc.so.6 #11 0x0000000000000000 in ?? () Thread 12 (Thread 0x7fffde0ea700 (LWP 32016)): #0 0x00007ffff572e2d4 in pthread_cond_wait@@GLIBC_2.3.2 () ---Type <return> to continue, or q <return> to quit--- from /lib/x86_64-linux-gnu/libpthread.so.0 #1 0x00007ffff59c120b in QWaitCondition::wait(QMutex*, unsigned long) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #2 0x00007ffff59bd1c7 in QSemaphore::acquire(int) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #3 0x00000000005f1f85 in SyntaxCheck::run (this=0x1c44fa0) at syntaxcheck.cpp:48 #4 0x00007ffff59c0d0b in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #5 0x00007ffff5729b50 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #6 0x00007ffff4cd4a7d in clone () from /lib/x86_64-linux-gnu/libc.so.6 #7 0x0000000000000000 in ?? () Thread 5 (Thread 0x7fffde8eb700 (LWP 30638)): #0 0x00007ffff4cce573 in select () from /lib/x86_64-linux-gnu/libc.so.6 #1 0x00007ffff5a99704 in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #2 0x00007ffff59c0d0b in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #3 0x00007ffff5729b50 in start_thread () from /lib/x86_64-linux-gnu/libpthread.so.0 #4 0x00007ffff4cd4a7d in clone () from /lib/x86_64-linux-gnu/libc.so.6 #5 0x0000000000000000 in ?? () Thread 1 (Thread 0x7ffff7fc5760 (LWP 30632)): ---Type <return> to continue, or q <return> to quit--- #0 0x00007ffff4c2c475 in raise () from /lib/x86_64-linux-gnu/libc.so.6 #1 0x00007ffff4c2f6f0 in abort () from /lib/x86_64-linux-gnu/libc.so.6 #2 0x00007ffff59b6722 in qt_message_output(QtMsgType, char const*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #3 0x00007ffff59b6a98 in ?? () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #4 0x00007ffff59b6c24 in qFatal(char const*, ...) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #5 0x00000000005c1da8 in LatexDocument::findStructureEntryBefore ( this=this@entry=0x1318210, iter=..., MapOfElements=..., linenr=linenr@entry=48, count=count@entry=1) at latexdocument.cpp:1594 #6 0x00000000005ca61c in LatexDocument::patchStructure (this=0x1318210, linenr=48, count=1) at latexdocument.cpp:283 #7 0x000000000076309e in LatexDocument::qt_static_metacall (_o=0x1318210, _c=<optimized out>, _id=15, _a=0x7fffffffc250) at .moc/moc_latexdocument.cpp:101 #8 0x00007ffff5ad154f in QMetaObject::activate(QObject*, QMetaObject const*, int, void**) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #9 0x000000000076a7dd in QDocument::contentsChange (this=<optimized out>, _t1=48, _t2=1) at .moc/moc_qdocument.cpp:276 #10 0x000000000068ea47 in QDocumentPrivate::emitContentsChange ( this=0x12212e0, line=48, lines=1) at qcodeedit/lib/document/qdocument.cpp:7597 #11 0x000000000069edbb in QDocumentInsertCommand::redo (this=0x1a8b8c0) ---Type <return> to continue, or q <return> to quit--- at qcodeedit/lib/document/qdocumentcommand.cpp:622 #12 0x00007ffff697ee03 in QUndoStack::push(QUndoCommand*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4 #13 0x0000000000685b16 in QDocumentPrivate::execute (this=0x12212e0, cmd=0x1a8b8c0) at qcodeedit/lib/document/qdocument.cpp:5913 #14 0x00000000006860c4 in QDocumentCursorHandle::insertText (this=0x146f6d0, s=..., keepAnchor=false) at qcodeedit/lib/document/qdocument.cpp:4880 #15 0x000000000065a2c5 in QEditor::insertText (this=this@entry=0x1cd6a20, c=..., text=...) at qcodeedit/lib/qeditor.cpp:4406 #16 0x000000000065be52 in QEditor::processEditOperation (this=0x1cd6a20, c=..., e=<optimized out>, op=QEditor::NoOperation) at qcodeedit/lib/qeditor.cpp:4257 #17 0x0000000000658834 in QEditor::keyPressEvent (this=0x1cd6a20, e=0x7fffffffd250) at qcodeedit/lib/qeditor.cpp:2899 #18 0x00007ffff6380e9b in QWidget::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4 #19 0x00007ffff672bd36 in QFrame::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4 #20 0x00007ffff67ab97b in QAbstractScrollArea::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4 #21 0x000000000064e0b8 in QEditor::event (this=0x1cd6a20, e=0x7fffffffd250) at qcodeedit/lib/qeditor.cpp:2539 #22 0x00007ffff633170c in QApplicationPrivate::notify_helper(QObject*, QEvent*) ---Type <return> to continue, or q <return> to quit--- () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4 #23 0x00007ffff6336704 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4 #24 0x00007ffff5abbb5e in QCoreApplication::notifyInternal(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #25 0x00007ffff63cea9a in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4 #26 0x00007ffff63ceed1 in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4 #27 0x00007ffff63abb28 in QApplication::x11ProcessEvent(_XEvent*) () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4 #28 0x00007ffff63d2bc2 in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4 #29 0x00007ffff40ea355 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #30 0x00007ffff40ea688 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #31 0x00007ffff40ea744 in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0 #32 0x00007ffff5aea276 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #33 0x00007ffff63d283e in ?? () from /usr/lib/x86_64-linux-gnu/libQtGui.so.4 #34 0x00007ffff5aba8af in QEventLoop::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #35 0x00007ffff5abab38 in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #36 0x00007ffff5abfcf8 in QCoreApplication::exec() () ---Type <return> to continue, or q <return> to quit--- from /usr/lib/x86_64-linux-gnu/libQtCore.so.4 #37 0x00000000004419c3 in main (argc=1, argv=<optimized out>) at main.cpp:172 Javier Domingo