[COCOA] Unclosable QPrinterDialog when calling QPrinterDialog::exec() after a QMessageBox::information() / Unvisible QPrinterDialog when calling QPrinterDialog::exec() after a QMessageBox::information()

When showing a QPrinterDialog after a call of QMessageBox::information(), in Qt 4.6.6 or 4.7.0 the QPrinterDialog will no longer close when clicking its buttons.
When doing the same thing from a slot in a mainwindow in Qt 4.7.0, the QPrinterDialog will not show ( show & close directly ).(Note: reproduced in 5.0.0)

More informations in the test case.
You should test the testcase with Qt 4.6.3 AND then with Qt 4.7.0, all in cocoa to expect to reproduce the bugs.