if getSaveFileDialog is called with proposed/default directory location it never opens the proposed directory rather always opens last visited directory.

This behavior is limited to OSX 10.8.2

This can be easily reproduced with following code:
QString fileName = QFileDialog::getSaveFileName(0, QString("Save File"),
"/usr/local/Trolltech/4.8.2-Test.png",
QString("Images (*.png *.xpm *.jpg)"));