==3888== 
==3888== Invalid read of size 8
==3888==    at 0x65C7657: operator-> (qscopedpointer.h:118)
==3888==    by 0x65C7657: qGetPtrHelper<QScopedPointer<QObjectData> > (qglobal.h:1038)
==3888==    by 0x65C7657: d_func (qwindow.h:98)
==3888==    by 0x65C7657: QWindow::destroy() (qwindow.cpp:1850)
==3888==    by 0x4FEF714: QWidgetPrivate::deleteTLSysExtra() (qwidget.cpp:1901)
==3888==    by 0x4FF4393: QWidget::destroy(bool, bool) (qwidget.cpp:12494)
==3888==    by 0x4FFA7A6: QWidget::~QWidget() (qwidget.cpp:1713)
==3888==    by 0x404AE40: QGLWidget::~QGLWidget() (qgl.cpp:3987)
==3888==    by 0x404AE56: QGLWidget::~QGLWidget() (qgl.cpp:3993)
==3888==    by 0x10AEF6: MainWindow::crash() (main.cpp:57)
==3888==    by 0x10B919: QtPrivate::FunctorCall<QtPrivate::IndexesList<>, QtPrivate::List<>, void, void (MainWindow::*)()>::call(void (MainWindow::*)(), MainWindow*, void**) (qobjectdefs_impl.h:152)
==3888==    by 0x10B89C: void QtPrivate::FunctionPointer<void (MainWindow::*)()>::call<QtPrivate::List<>, void>(void (MainWindow::*)(), MainWindow*, void**) (qobjectdefs_impl.h:185)
==3888==    by 0x10B806: QtPrivate::QSlotObject<void (MainWindow::*)(), QtPrivate::List<>, void>::impl(int, QtPrivate::QSlotObjectBase*, QObject*, void**, bool*) (qobjectdefs_impl.h:414)
==3888==    by 0x5802016: call (qobjectdefs_impl.h:394)
==3888==    by 0x5802016: QMetaObject::activate(QObject*, int, int, void**) (qobject.cpp:3776)
==3888==    by 0x58024FA: QMetaObject::activate(QObject*, QMetaObject const*, int, void**) (qobject.cpp:3648)
==3888==  Address 0xbd05df8 is 8 bytes inside a block of size 88 free'd
==3888==    at 0x4C3123B: operator delete(void*) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3888==    by 0x5018FEB: QWidgetWindow::~QWidgetWindow() (qwidgetwindow.cpp:166)
==3888==    by 0x5807EAF: QObjectPrivate::deleteChildren() (qobject.cpp:2010)
==3888==    by 0x58093E1: QObject::~QObject() (qobject.cpp:1032)
==3888==    by 0x65C75F3: QWindow::~QWindow() (qwindow.cpp:214)
==3888==    by 0x5018F3A: QWidgetWindow::~QWidgetWindow() (qwidgetwindow.cpp:164)
==3888==    by 0x5018FDE: QWidgetWindow::~QWidgetWindow() (qwidgetwindow.cpp:166)
==3888==    by 0x4FEF72B: QWidgetPrivate::deleteTLSysExtra() (qwidget.cpp:1903)
==3888==    by 0x4FF4393: QWidget::destroy(bool, bool) (qwidget.cpp:12494)
==3888==    by 0x4FFA7A6: QWidget::~QWidget() (qwidget.cpp:1713)
==3888==    by 0x50EB8D9: QDockWidget::~QDockWidget() (qdockwidget.cpp:1293)
==3888==    by 0x50EB8EE: QDockWidget::~QDockWidget() (qdockwidget.cpp:1294)
==3888==  Block was alloc'd at
==3888==    at 0x4C3017F: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==3888==    by 0x4FE84B3: QWidgetPrivate::createTLSysExtra() (qwidget.cpp:1539)
==3888==    by 0x4FF1DE0: QWidget::setAttribute(Qt::WidgetAttribute, bool) (qwidget.cpp:11341)
==3888==    by 0x5000C40: QWidgetPrivate::init(QWidget*, QFlags<Qt::WindowType>) (qwidget.cpp:1181)
==3888==    by 0x5000DDF: QWidget::QWidget(QWidgetPrivate&, QWidget*, QFlags<Qt::WindowType>) (qwidget.cpp:1046)
==3888==    by 0x404C856: QGLWidget::QGLWidget(QWidget*, QGLWidget const*, QFlags<Qt::WindowType>) (qgl.cpp:3883)
==3888==    by 0x10ACFB: MainWindow::MainWindow(QWidget*) (main.cpp:42)
==3888==    by 0x10AFAF: main (main.cpp:65)
==3888==