Comment 93 for bug 1003950

The command below reserrects the hidden "Software Updater" window when issued. It does not fix the underlying coding issues however it makes it possibly to continue the update process without killing/quitting - restarting the app.

sudo apt-get install wmctrl # if necessary
wmctrl -R 'Software Updater'

after issuing the command the window should appear and respond to its controls as normal.

Hope this help... I take no credit as this is a repeat from one of the posts higher up in this thread