[REG: 5.x - 4.x] Program hangs when plugging/unplugging usb devices if there are too many native widgets.

#0  pthread_cond_wait@@GLIBC_2.3.2 () at ../sysdeps/unix/sysv/linux/x86_64/pthread_cond_wait.S:185
#1  0x00007fffeff94eb9 in _xcb_conn_wait (c=c@entry=0x630fb0, cond=cond@entry=0x7fffffffd200, vector=vector@entry=0x0, count=count@entry=0x0) at ../../src/xcb_conn.c:427
#2  0x00007fffeff96617 in wait_for_reply (c=c@entry=0x630fb0, request=682647, e=e@entry=0x7fffffffd2d0) at ../../src/xcb_in.c:516
#3  0x00007fffeff96721 in xcb_wait_for_reply (c=0x630fb0, request=682647, e=0x7fffffffd2d0) at ../../src/xcb_in.c:546
#4  0x00007ffff0608a47 in _XReply () from /usr/lib/x86_64-linux-gnu/libX11.so.6
#5  0x00007fffef23f32f in XIQueryDevice () from /usr/lib/x86_64-linux-gnu/libXi.so.6
#6  0x00007ffff7ed15d6 in QXcbConnection::xi2SetupDevices (this=0x62f9e0) at qxcbconnection_xi2.cpp:117
#7  0x00007ffff7ed5ca3 in QXcbConnection::xi2HandleHierachyEvent (this=0x62f9e0, event=0x9ed140) at qxcbconnection_xi2.cpp:831
#8  0x00007ffff7ed3a4b in QXcbConnection::xi2HandleEvent (this=0x62f9e0, event=0x9ed140) at qxcbconnection_xi2.cpp:523
#9  0x00007ffff7e90d7e in QXcbConnection::handleXcbEvent (this=0x62f9e0, event=0x9ed140) at qxcbconnection.cpp:1223
#10 0x00007ffff7e929eb in QXcbConnection::processXcbEvents (this=0x62f9e0) at qxcbconnection.cpp:1735
#11 0x00007ffff7ee108a in QXcbConnection::qt_static_metacall (_o=0x62f9e0, _c=QMetaObject::InvokeMetaMethod, _id=1, _a=0x7fffe4004a40) at .moc/moc_qxcbconnection.cpp:188
#12 0x00007ffff7270d99 in QMetaCallEvent::placeMetaCall (this=0x7fffe4003b80, object=0x62f9e0) at kernel/qobject.cpp:502
#13 0x00007ffff7271f63 in QObject::event (this=0x62f9e0, e=0x7fffe4003b80) at kernel/qobject.cpp:1263
#14 0x00007ffff7e9408b in QXcbConnection::event (this=0x62f9e0, e=0x7fffe4003b80) at qxcbconnection.cpp:2351
#15 0x00007ffff76d80ae in QApplicationPrivate::notify_helper (this=0x61dc50, receiver=0x62f9e0, e=0x7fffe4003b80) at kernel/qapplication.cpp:3799
#16 0x00007ffff76d52fc in QApplication::notify (this=0x7fffffffe340, receiver=0x62f9e0, e=0x7fffe4003b80) at kernel/qapplication.cpp:3159
#17 0x00007ffff723350b in QCoreApplication::notifyInternal2 (receiver=0x62f9e0, event=0x7fffe4003b80) at kernel/qcoreapplication.cpp:988
#18 0x00007ffff723786e in QCoreApplication::sendEvent (receiver=0x62f9e0, event=0x7fffe4003b80) at ../../include/QtCore/../../src/corelib/kernel/qcoreapplication.h:231
#19 0x00007ffff7234a26 in QCoreApplicationPrivate::sendPostedEvents (receiver=0x0, event_type=0, data=0x61ddc0) at kernel/qcoreapplication.cpp:1649
#20 0x00007ffff723437c in QCoreApplication::sendPostedEvents (receiver=0x0, event_type=0) at kernel/qcoreapplication.cpp:1503
#21 0x00007ffff72b919d in postEventSourceDispatch (s=0x64d9c0) at kernel/qeventdispatcher_glib.cpp:276
#22 0x00007ffff48c51a7 in g_main_context_dispatch () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#23 0x00007ffff48c5400 in ?? () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#24 0x00007ffff48c54ac in g_main_context_iteration () from /lib/x86_64-linux-gnu/libglib-2.0.so.0
#25 0x00007ffff72b99a8 in QEventDispatcherGlib::processEvents (this=0x64da50, flags=...) at kernel/qeventdispatcher_glib.cpp:423
#26 0x00007ffff7ee2452 in QPAEventDispatcherGlib::processEvents (this=0x64da50, flags=...) at eventdispatchers/qeventdispatcher_glib.cpp:121
#27 0x00007ffff722fb48 in QEventLoop::processEvents (this=0x7fffffffe2c0, flags=...) at kernel/qeventloop.cpp:134
#28 0x00007ffff722fe7f in QEventLoop::exec (this=0x7fffffffe2c0, flags=...) at kernel/qeventloop.cpp:210
#29 0x00007ffff7233d01 in QCoreApplication::exec () at kernel/qcoreapplication.cpp:1261
#30 0x00007ffff603ebf2 in QGuiApplication::exec () at kernel/qguiapplication.cpp:1639
#31 0x00007ffff76d4ca3 in QApplication::exec () at kernel/qapplication.cpp:2975
#32 0x0000000000402fa0 in main (argc=1, argv=0x7fffffffe488) at test.cpp:42