Thread 1 "qseq66" received signal SIGSEGV, Segmentation fault.
0x00007ffff7a8cc6c in QWidgetItem::isEmpty() const () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
(gdb) bt
#0 0x00007ffff7a8cc6c in QWidgetItem::isEmpty() const () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#1 0x00007ffff7a8da9e in QWidgetItemV2::minimumSize() const () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#2 0x00007ffff7a85f55 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#3 0x00007ffff7a864c9 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#4 0x00007ffff7a86f91 in QGridLayout::minimumSize() const () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#5 0x00007ffff7a85f55 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#6 0x00007ffff7a87317 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#7 0x00007ffff7a880e7 in QGridLayout::setGeometry(QRect const&) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#8 0x00007ffff7a89618 in QLayoutPrivate::doResize(QSize const&) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#9 0x00007ffff7a8a72f in QLayout::activate() () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#10 0x00007ffff7aabcd7 in QWidgetPrivate::setVisible(bool) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#11 0x00007ffff72be551 in seq66::qslivegrid::create_one_button (this=0x55555593cc20, seqno=0) at qslivegrid.cpp:425
#12 0x00007ffff72bdcf2 in seq66::qslivegrid::create_loop_buttons (this=0x55555593cc20) at qslivegrid.cpp:283
#13 0x00007ffff72be733 in seq66::qslivegrid::paintEvent (this=0x55555593cc20) at qslivegrid.cpp:452
#14 0x00007ffff7aac2b6 in QWidget::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#15 0x00007ffff7b59d52 in QFrame::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#16 0x00007ffff7a69a66 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#17 0x00007ffff7a730f0 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#18 0x00007ffff763c93a in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#19 0x00007ffff7aa4f4a in QWidgetPrivate::sendPaintEvent(QRegion const&) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#20 0x00007ffff7aa5799 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#21 0x00007ffff7aa6423 in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#22 0x00007ffff7aa54a4 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#23 0x00007ffff7aa6423 in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#24 0x00007ffff7aa54a4 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#25 0x00007ffff7aa6423 in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#26 0x00007ffff7aa6306 in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#27 0x00007ffff7aa54a4 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#28 0x00007ffff7aa6423 in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#29 0x00007ffff7aa54a4 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#30 0x00007ffff7aa6423 in QWidgetPrivate::paintSiblingsRecursive(QPaintDevice*, QList<QObject*> const&, int, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#31 0x00007ffff7aa54a4 in QWidgetPrivate::drawWidget(QPaintDevice*, QRegion const&, QPoint const&, int, QPainter*, QWidgetBackingStore*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#32 0x00007ffff7a7bbfc in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#33 0x00007ffff7a7bdc1 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#34 0x00007ffff7a94385 in QWidgetPrivate::syncBackingStore() () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#35 0x00007ffff7aaccac in QWidget::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#36 0x00007ffff7bc1148 in QMainWindow::event(QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#37 0x00007ffff7a69a66 in QApplicationPrivate::notify_helper(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#38 0x00007ffff7a730f0 in QApplication::notify(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Widgets.so.5
#39 0x00007ffff763c93a in QCoreApplication::notifyInternal2(QObject*, QEvent*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#40 0x00007ffff763f5b8 in QCoreApplicationPrivate::sendPostedEvents(QObject*, int, QThreadData*) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#41 0x00007ffff7694f67 in ?? () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#42 0x00007ffff5c41fbd in g_main_context_dispatch () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#43 0x00007ffff5c42240 in ?? () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#44 0x00007ffff5c422e3 in g_main_context_iteration () from /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0
#45 0x00007ffff7694565 in QEventDispatcherGlib::processEvents(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#46 0x00007ffff763b4db in QEventLoop::exec(QFlags<QEventLoop::ProcessEventsFlag>) () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#47 0x00007ffff7643246 in QCoreApplication::exec() () from /usr/lib/x86_64-linux-gnu/libQt5Core.so.5
#48 0x00007ffff72e8619 in seq66::qt5nsmanager::run (this=0x7fffffffd820) at qt5nsmanager.cpp:146
#49 0x00005555555566ea in main (argc=1, argv=0x7fffffffd9b8) at seq66qt5.cpp:107
The window that appears is a little odd to me, but I'm not sure if that's the issue. I'd be happy to debug this more.