on starting xfce4 a large number of identical messages are output to the 
console.

*** attempt to put segment in horiz list twice

I seem to have all required elements on the panel so I am not sure of the cause 
or effect of this error.

Reproducible: Always
Steps to Reproduce:
1. startxfce4
2. quit (or Alt-F1 to console)
3. read screenful of identical messages.



Expected Results:  
clean start of more helpful message to solve error.