xfce4-panel-dev 4.4.0-0ubuntu1.1 (i386 binary) in ubuntu feisty

 In this package, you can find the development files
 distributed with the Xfce4 panel, the main panel of
 Xfce4 desktop environment. The files in this package
 are mainly going to be of interest for you if you
 intend to code applications which use some of the
 Xfce4 C panel functions.
 .
 Homepage: http://www.xfce.org/