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In Gnome3 if there are glitches in the desktop, you can run Alt-F2,r and the shell is restarted.
Is there anything similar in XFCE, that is restarting the shell without closing all programs, logging out and in again?
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Xfce is modular so it depends on which module is problematic. Most can be restarted on the fly, however, the session manager (xfce4-session) can not and you need to log out and back in again to restart it.
Desktop = "xfdesktop --reload" or "kill -HUP `pidof xfdesktop`"
Window Manager = "xfwm4 --replace"
Settings Daemon = "xfsettingsd --replace"
Panel = "xfce4-panel -r"
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