Here is the stack with libqt4-dbg, 4:4.8.5 version :
(gdb) start
Function "main" not defined.
Make breakpoint pending on future shared library load? (y or [n])
Starting program: /usr/bin/x2goclient
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib/i386-linux-gnu/libthread_db.so.1".
x2go-INFO-1> "Starting x2goclient..."
x2go-INFO-4> "Translator: :/x2goclient_fr_fr installed."
x2go-INFO-5> "Translator: :/qt_fr_FR installed."
x2go-INFO-3> "Started x2goclient."
x2go-INFO-8> "Starting connection to server:
192.168.1.11:22"
[New Thread 0xb2e62b40 (LWP 31128)]
Program received signal SIGSEGV, Segmentation fault.
QString::operator= (this=0xbffff024, other=...) at tools/qstring.cpp:1410
1410 tools/qstring.cpp: Aucun fichier ou dossier de ce type.
(gdb) bt
#0 QString::operator= (this=0xbffff024, other=...) at tools/qstring.cpp:1410
#1 0x080a7cdc in ?? ()
#2 0x080a89b6 in ?? ()
#3 0x0814420e in ?? ()
#4 0xb6fc80f7 in QMetaObject::activate (sender=0x8537c08, m=0x8155698, local_signal_index=0,
argv=0xbffff4d0) at kernel/qobject.cpp:3539
#5 0x08145a1f in ?? ()
#6 0x08105b81 in ?? ()
#7 0x08145c68 in ?? ()
#8 0xb6fc48aa in QMetaCallEvent::placeMetaCall (this=0xb3311408, object=0x8537c08) at kernel/qobject.cpp:524
#9 0xb6fcc6fb in QObject::event (this=0x8537c08, e=0xb3311408) at kernel/qobject.cpp:1194
#10 0xb73a37f4 in QApplicationPrivate::notify_helper (this=0x8288f38, receiver=0x8537c08, e=0xb3311408)
at kernel/qapplication.cpp:4567
#11 0xb73aa2d3 in QApplication::notify (this=0xbffffb58, receiver=0x8537c08, e=0xb3311408)
at kernel/qapplication.cpp:4353
#12 0xb6fb2e4a in QCoreApplication::notifyInternal (this=0xbffffb58, receiver=receiver@entry=0x8537c08,
event=event@entry=0xb3311408) at kernel/qcoreapplication.cpp:953
#13 0xb6fb670d in sendEvent (event=0xb3311408, receiver=0x8537c08)
at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#14 QCoreApplicationPrivate::sendPostedEvents (receiver=receiver@entry=0x0, event_type=event_type@entry=0,
data=0x8289048) at kernel/qcoreapplication.cpp:1577
#15 0xb6fb6c1c in QCoreApplication::sendPostedEvents (receiver=receiver@entry=0x0,
event_type=event_type@entry=0) at kernel/qcoreapplication.cpp:1470
#16 0xb6fe323e in sendPostedEvents () at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:236
#17 postEventSourceDispatch (s=0x8289da0) at kernel/qeventdispatcher_glib.cpp:287
#18 0xb65df1e3 in g_main_context_dispatch () from /lib/i386-linux-gnu/libglib-2.0.so.0
#19 0xb65df468 in ?? () from /lib/i386-linux-gnu/libglib-2.0.so.0
#20 0xb65df528 in g_main_context_iteration () from /lib/i386-linux-gnu/libglib-2.0.so.0
#21 0xb6fe293b in QEventDispatcherGlib::processEvents (this=this@entry=0x8289b68, flags=...)
at kernel/qeventdispatcher_glib.cpp:434
#22 0xb74585de in QGuiEventDispatcherGlib::processEvents (this=0x8289b68, flags=...)
at kernel/qguieventdispatcher_glib.cpp:204
#23 0xb6fb1823 in QEventLoop::processEvents (this=this@entry=0xbffffad8, flags=...)
at kernel/qeventloop.cpp:149
#24 0xb6fb1b49 in QEventLoop::exec (this=this@entry=0xbffffad8, flags=...) at kernel/qeventloop.cpp:204
---Type <return> to continue, or q <return> to quit---
#25 0xb6fb78fe in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1225
#26 0xb73a1a24 in QApplication::exec () at kernel/qapplication.cpp:3828
#27 0x0812a533 in ?? ()
#28 0x0805bd3b in ?? ()
#29 0xb6b81a83 in __libc_start_main (main=0x805bd20, argc=1, argv=0xbffffc94, init=0x8148de0,
fini=0x8148e50, rtld_fini=0xb7fed180 <_dl_fini>, stack_end=0xbffffc8c) at libc-start.c:287
#30 0x0805bdc1 in ?? ()
I'm not a C/C++ developer so this is difficult to me to investigate that.