python - How can I disable clear of clipboard on exit of PyQt application?

Question

I have a simple PyQt4 application (see the code below) that reveals a problem: if I select the text from a QLineEdit and copy it to the clipboard, then I can paste it to another application only while my application is running. It seems that on exit, PyQt application clears the clipboard so I can't paste the text after the application is closed.

What can I do to avoid this problem?

PyQt 4.4.3 @ Python 2.5 @ Windows XP. Also this effect confirmed on PyQt 4.5+, and on Linux too.

import sys
from PyQt4 import QtGui
app = QtGui.QApplication(sys.argv)
edit = QtGui.QLineEdit()
edit.setText('foo bar')
edit.show()
app.exec_()

Answer 1

OK, there is not exactly clear of clipboard occurs. Just QT store some sort of pointer of text in the clipboard instead of just text. Gordon Tyler has pointed me to this discussion on the PyQt mailing list which explains what's going on. I quote code and relevant part of explanation.

Run this code on exit of application (e.g. in closeEvent handler):

   from PyQt4 import QtGui, QtCore
   clipboard = QtGui.QApplication.clipboard()
   event = QtCore.QEvent(QtCore.QEvent.Clipboard)
   QtGui.QApplication.sendEvent(clipboard, event)

The basic concept behind this is that by default copying something into the clipboard only copies a reference/pointer to the source application. Then when another application wants to paste the data from the clipboard it requests the data from the source application. Calling OleFlushClipboard causes Windows to copy the real data into the clipboard instead of the reference. While this does cause a delay when copying images, it should not have any noticeable impact with strings.

The code above is pretty cross-platform and don't make any bad impact on Linux platform.