Similar to bug 667552 for the app switcher, attached modal dialogs
can result in an unexpected window order in the window switcher:
Selecting a window with an attached dialog will focus the dialog
instead, but as the dialog itself is ignored in the window list,
its last-used timestamp is not taken into account for the position
in the MRU list. Fix this by fetching the list of all NORMAL windows
and filter out skip-taskbar windows ourselves, while making sure that
windows appear in the position of their attached modal dialog where
appropriate.
https://bugzilla.gnome.org/show_bug.cgi?id=747153
d4ce51b1b7