start xfce4-panel with english as menu language without changing the default language of the desktop

Hi,

I try immediately after the new login as non-root user on the desktop start

LC_ALL=C xfce4-panel --preferences

with English as menu language without changing the default language of the desktop. It opens a window panel preferences but with the default language of the desktop (German). Is this behavior to be considered as an error?

FYI: Entering LC_ALL=C xfce4-appfinder

leads to the desired result - the "Application Finder" window opens with English as menu language.

How can I start the "Panel preferences" window with English as menu language without changing the default desktop language?