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This issue shows in thunar because of an issue in an underlying library (Gtk / GLib / Gio / Gvfs /...)
A link to the underlying issue should be added to the thunar issue. It might sense to keep to thunar issue open in order to implement a workaround.
5. Action Buttons
Xfce / xfce4-panel
Plugin that show buttons for session management or them in a context menu
5. Appearance Settings
Xfce / xfce4-panel
Settings found on the Appearance tab of the Panel Preferences dialog
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