Shut down TabbedBrowser in MainWindow closeEvent.

Hopefully fixes #197.

qutebrowser/app.py

@@ -638,12 +638,8 @@ class Application(QApplication):
             self.removeEventFilter(self._event_filter)
         except AttributeError:
             pass
-        # Close all tabs
-        for win_id in objreg.window_registry:
-            log.destroy.debug("Closing tabs in window {}...".format(win_id))
-            tabbed_browser = objreg.get('tabbed-browser', scope='window',
-                                        window=win_id)
-            tabbed_browser.shutdown()
+        # Close all windows
+        QApplication.closeAllWindows()
         # Shut down IPC
         try:
             objreg.get('ipc-server').shutdown()

qutebrowser/widgets/mainwindow.py

@@ -333,3 +333,4 @@ class MainWindow(QWidget):
         e.accept()
         objreg.get('app').geometry = bytes(self.saveGeometry())
         log.destroy.debug("Closing window {}".format(self.win_id))
+        self._tabbed_browser.shutdown()

qutebrowser/widgets/webview.py

@@ -264,6 +264,7 @@ class WebView(QWebView):
         """Shut down the webview."""
         # We disable javascript because that prevents some segfaults when
         # quitting it seems.
+        log.destroy.debug("Shutting down {!r}.".format(self))
         settings = self.settings()
         settings.setAttribute(QWebSettings.JavascriptEnabled, False)
         self.stop()