* Fixes "'DetailsPanel' object has no attribute '_table'" error on shutdown if the Results table is updated (item removed) while the Details Dialog is shown as a floating window.
* It seems that QApplication.quit() triggers some sort of refresh on the floating QDockWidget, which in turn makes calls to the underlying model that is possibly being destroyed, ie. there might be a race condition here.
* Closing or hiding the QDockWidget before the cal to quit() is a workaround. Similarly, this is already done in the quitTriggered() method anyway.
* This fixes#857.