On Xubuntu the Status Notifier plugin (pacakge name : xfce4-statusnotifier-plugin) works natively, it's the default plugin that manage the Network Manager applet, which means it is this plugin that displays the little Wi-Fi icon on the panel.
On Debian XFCE however the default plugin for the NM applet is the Notification Area.
I'm trying to install the Status Notifier plugin on Debian to replace the Notification Area but I can't make it work, the plugin doesn't display any item. The xfce4-statusnotifier-plugin documentation says :
Known Issues
Plugin Doesn't Show Any ItemsThere is already a running service which works with status notifier items. Most probably it's the indicator-application service which is used by xfce4-indicator-plugin. Make sure this service is not running: remove this indicator from xfce4-indicator-plugin and remove the service from autostart.
But I don't understand it. Plus I don't have the same scenario since I don't have the xfce4-indicator plugin installed. In my case I think the problem is the Notification Area.