As far as I understand, it is the window manager that primarily decides whether to give focus to a new window. That said, apps can to things that affect how window managers do things. In particular, I think update-manager should make all of its dialogs transient for the main window. See "Transient for Window" atribute in Glade.
As far as I understand, it is the window manager that primarily decides whether to give focus to a new window. That said, apps can to things that affect how window managers do things. In particular, I think update-manager should make all of its dialogs transient for the main window. See "Transient for Window" atribute in Glade.