xfce4-panel won't reload plugins

[Bill Mill]

I am trying to learn how to develop plugins for the panel. I have the 
plugin sample, but I cannot get the plugin list to refresh with the 
"killall -USR1 xfce4-panel". This problem was already reported 
(http://varmint.moongroup.com/pipermail/xfce4-dev/2003-July/005793.html), 
but no resolution was offered in that thread.

When I run killall (or pkill) I see the panel disappear and then 
reappear. However, the plugins list is the same. I couldn't find any 
error messages about it. If you tell me how to look for debugging info, 
I'd be glad to help you out.

This occurred with both the systemload plugin and the sample plugin. I 
am running RH9, with xfce release 4.0.0.

Peace
Bill Mill