Still not able to test on HEAD so apologies if this is fixed.

According to the documentation you should be able to create and instance of
QThread, call thread.start() and have it run. It doesn't work in PySide how
ever (the difference between exec() and exec_()?)

Here are acouple of scratches, the first one never launches the GUI window.

import sys
from PySide import QtCore, QtGui

def main():
    app = QtGui.QApplication(sys.argv)
    mainWindow = QtGui.QMainWindow()
    mainWindow.show()
    thread = QtCore.QThread()
    thread.start()
    app.exec_()

if __name__ == '__main__':
    main()

Can fix the problem by implementing run and calling exec_:

import sys
from PySide import QtCore, QtGui

class MyThread(QtCore.QThread):
    def run(self):
        self.exec_()

def main():
    app = QtGui.QApplication(sys.argv)
    mainWindow = QtGui.QMainWindow()
    mainWindow.show()
    thread = MyThread()
    thread.start()
    app.exec_()

if __name__ == '__main__':
    main()