QFileDialog has memory leak.

Use of the the static function QFileDialog::getExistingDirectory(...) causes several megabytes of memory to be allocated when the dialog is shown, but this memory is not released afterwards. This bug can easily be demonstrated using the 'StandardDialogs' example which comes with Qt. I have produced the bug using both static and dynamically linked versions of the Qt library (which I built myself) on the Windows platform.

Please follow the following steps to observe the problem:

1) Launch the 'Standard Dialogs' example which comes with Qt.
2) Open the Windows Task Manager and note how much memory is being used (10Mb on my system).
3) Press the button labelled QFileDialog::getExistingDirectory()
4) Observe the memory usage increase (to 19Mb on my system).
5) Press cancel on the dialog. Observe that the memory remains high and does not return to the previous level.

Note that this procedure only works once per run of the application. To see it again you need to exit the sample application and run it again.