Update DownloadView geometry when MainWindow size changed.

qutebrowser/widgets/mainwindow.py

@@ -136,6 +136,7 @@ class MainWindow(QWidget):
         """
         super().resizeEvent(e)
         self.resize_completion()
+        self.downloadview.updateGeometry()
 
     def closeEvent(self, e):
         """Override closeEvent to display a confirmation if needed."""