[PySide] Error on Ubuntu but not Windows

[Jim Byrnes]

I am running Ubuntu 12.04, PySide 1.2.2.

I am just getting started with PySide and have been watching a series of 
video tutorials. In the video on threading there is the following program.

from PySide.QtCore import *
from PySide.QtGui import *
import sys
import showGui
import time
import showGui

class MainDialog(QDialog, showGui.Ui_mainDialog):

     def __init__(self, parent=None):
         super(MainDialog, self).__init__(parent)
         self.setupUi(self)

         self.showButton.setText("Process")
         self.connect(self.showButton, SIGNAL("clicked()"), 
self.processData)

         self.workerThread = WorkerThread()
         self.connect(self.workerThread, SIGNAL("threadDone(QString, 
QString)"), self.threadDone, Qt.DirectConnection)

     def processData(self):
         self.workerThread.start()
         QMessageBox.information(self, "Done!", "Done.")

     def threadDone(self, text, text2):
         # Does not work.  Gives pixmaps error
         #QMessageBox.warning(self, "Warning!", "Thread execution 
completed!")
         # Works as expected
         self.nameEdit.setText("Worker thread finished processing.")
         print text
         print text2

class WorkerThread(QThread):

     def __init__(self, parent=None):
         super(WorkerThread, self).__init__(parent)

     def run(self):
         time.sleep(3)
         self.emit(SIGNAL("threadDone(QString, QString)"), "Confirmation 
that the thread is finished.", "Another confirmation that the thread has 
been compledted.")

app = QApplication(sys.argv)
form = MainDialog()
form.show()
app.exec_()

In the threadDone method uncommenting the QMessageBox line produces the 
following error message:

QObject::setParent: Cannot set parent, new parent is in a different thread
QPixmap: It is not safe to use pixmaps outside the GUI thread
QPixmap: It is not safe to use pixmaps outside the GUI thread
QPixmap: It is not safe to use pixmaps outside the GUI thread
QPixmap: It is not safe to use pixmaps outside the GUI thread
QPixmap: It is not safe to use pixmaps outside the GUI thread
QPixmap: It is not safe to use pixmaps outside the GUI thread
QPixmap: It is not safe to use pixmaps outside the GUI thread
X Error: BadImplementation (server does not implement operation) 17
   Major opcode: 20 (X_GetProperty)
   Resource id:  0x0
[xcb] Unknown sequence number while processing queue
[xcb] Most likely this is a multi-threaded client and XInitThreads has 
not been called
[xcb] Aborting, sorry about that.
python2.7: ../../src/xcb_io.c:274: poll_for_event: Assertion 
`!xcb_xlib_threads_sequence_lost' failed.

Process finished with exit code 134

In the video the presenter is running Windows 8  and it worked for him. 
  Is this a known problem or am I just doing something wrong? I don't 
have a window machine to try it locally.

Thanks,  Jim