Datetime plugin is configured with layout 'Time only'.
When xfce4-panel start, the plugin display the time and the date. After 10 seconds, the plugin display only the time (correct behavior).
Created attachment 1061
patch to fix this issue
This patch simply call datetime_update after gtk_widget_show_all in datetime_new.
ty. will be merged in trunk
fixed in svn rev. 2654.