screenGeometry() of a virtual machine (VMware, guest WinXP) is read wrong

Screen width and Screen height is always, regarding less to size of actual WinXP virtual machine:

Screen width: 1448
Screen height: 853

VMware tools are installed. Python with tkinter or with wx works fine on the same wirtual machine.
Code runs under debian jessy. export DISPLAY=192.168.0.44:0.0 , then windows are send to VMWare virtual maschine.

PySide Code:

def main():
#Init app
qt_app = QApplication(sys.argv)

global MESSAGE
init_message(message="blah-blah, blah-blah. " * 7)
screen = QDesktopWidget().screenGeometry()
size = MESSAGE.geometry()
MESSAGE.move((screen.width()-size.width())/2, (screen.height()-size.height())/2)

MESSAGE.show()
qt_app.exec_()
print "width: ", size.width()
print "height: ", size.height()
print "Screen width: ", screen.width()
print "Screen height: ", screen.height()

print "MESSAGE closed."

Workaround: calculate screen dimensions using tkinter or wx.