Reproduce bug:

* In Xfce4: »Settings Manager/Window Manager/Keyboard/Switch window for same application« choose any shortcut (default: Super + Tab).

* Open several instances of »evince« (or »xterm«, »gnome-calculator«, »abiword«, »vlc«).

* Try to switch between the windows with your shortcut for »Switch window for same application«.

Result:

You cannot switch between windows for the same application. As opposed to this open several windows of »mousepad« (or »xfce4-terminal«, »firefox«, »libreoffice --writer«, ...) to see how the shortcut should work correctly.

Tested with Xubuntu (32/64 Bit) and ArchLinux/xfce4 (32/64 Bit)