how to compile plugin

[Morico Stéphane]

hi,
I have a stupid question....
I'm writing a small GTK application to configure xkb map...
Now, I want to transform it into xfce plugin...

To start, I'm looking the xfce sample plugin...
I tried to compile  xfce4-sample-plugin-0.1.2 but it don't work...

./configure :
....
checking for xfce4-panel-1.0 >= 0.10.1... Package xfce4-panel-1.0 was
not found in the pkg-config search path.
Perhaps you should add the directory containing `xfce4-panel-1.0.pc'
to the PKG_CONFIG_PATH environment variable
No package 'xfce4-panel-1.0' found

configure: error: Library requirements (xfce4-panel-1.0 >= 0.10.1) not
met; consider adjusting the PKG_CONFIG_PATH environment variable if your
libraries are in a nonstandard prefix so pkg-config can find them.

export PKG_CONFIG_PATH=/usr/src/xfce-4.0.5/src/xfce4-panel-4.0.5/panel/ 
does not work...