C++11 thread in qt 5

//MainWindow.cpp
 void MainWindow::threadedFunction()
{
    myDialog = new MyDialogs(list,processList,this);
    myDialog->show();
}

void MainWindow::createNewDialog()
{
   getProcesses();
   //threadedFunction();  //This works fine.
   std::thread tx = std::thread(&MainWindow::threadedFunction,this);
   tx.join();
}

//MyDialog.cpp

MyDialogs::MyDialogs(QList<int> lists,QStringList list,QObject *parent):QDialog(0)
{

    QVBoxLayout *toplay = new QVBoxLayout(this);
    listWidget = new QListWidget(this);

    x<<list;
    l<<lists;
    listWidget->addItems(x);
    toplay->addWidget(listWidget);


       connect(listWidget,SIGNAL(doubleClicked(QModelIndex)),
          this,SLOT(getProcessString(QModelIndex)));
}

void MyDialogs::getProcessString(QModelIndex index)
{
    selectedProcessString = index.data().toString();
    rowIndex = index.row();
}

Already set in pro file.

CONFIG += c++11

when I call threadedFunction directly the code works fine. But the above mentioned code gives me runtime error. If I use only qDebug statements in threadedFunction and remove myDialog code, the code runs fine even with the threads. What is the problem?