[Vala] Generated vapi file for a library not compilable.

[PCMan <pcman tw gmail com>]

Hello,
I got another issue with vala.
I moved the core part of my program to a separate library, and let the main
program call that library.
The library itself compiles correctly.
However, the genrated vapi file is not usable by the main program.
Both parts are written in vala.
The generated vapi file looks like this.

When compiling the main program with --pkg <my_vapi_file>, I got errors.
The generated vapi file seems to have duplicated nested namespace for
static methods like this.

namespace Lxpanel {

class Applet : Object {
    static Lxpanel.Applet? from_file(string...);
}
}

If I remove Lxpanel.Applet manually and just use Applet, it works.
I like vala a lot and want to continue use it for my project, so I hope
that someone knows how to fix it. Otherwise I may have to rewrite the
program in plain C/GObject, which is a pain. :-(

All of the errors I got are like these:
  VALAC  lxpanel2_vala.stamp
lxpanel-applet.vapi:10.27-10.49: error: The type name `Lxpanel.AppletInfo'
could not be found
public static GLib.List<weak Lxpanel.AppletInfo> get_all_types ();
                        ^^^^^^^^^^^^^^^^^^^^^^^
lxpanel-applet.vapi:13.10-13.35: error: The type name `Lxpanel.AppletInfo'
could not be found
public unowned Lxpanel.AppletInfo get_info ();
       ^^^^^^^^^^^^^^^^^^^^^^^^^^
lxpanel-applet.vapi:18.17-18.30: error: The type name `Lxpanel.Applet'
could not be found
public static Lxpanel.Applet? new_from_type_name (string type_name);
              ^^^^^^^^^^^^^^
lxpanel-applet.vapi:19.44-19.61: error: The type name `Lxpanel.AppletInfo'
could not be found
public static void register_applet_info (Lxpanel.AppletInfo info);
                                         ^^^^^^^^^^^^^^^^^^
lxpanel-applet.vapi:34.10-34.29: error: The type name
`Lxpanel.AppletModule' could not be found
public Lxpanel.AppletModule? module;
       ^^^^^^^^^^^^^^^^^^^^
lxpanel-applet.vapi:40.10-40.23: error: The type name `Lxpanel.Applet'
could not be found
public Lxpanel.Applet? create_new ();
       ^^^^^^^^^^^^^^
lxpanel-applet.vapi:41.17-41.34: error: The type name `Lxpanel.AppletInfo'
could not be found
public static Lxpanel.AppletInfo? from_file (string applet_id, string
info_path);
              ^^^^^^^^^^^^^^^^^^
lxpanel-applet.vapi:74.24-74.37: error: The type name `Lxpanel.Button'
could not be found
public class Drawer : Lxpanel.Button {
                      ^^^^^^^^^^^^^^
lxpanel-applet.vapi:75.13-75.25: error: The type name `Lxpanel.Popup' could
not be found
protected Lxpanel.Popup? popup;
          ^^^^^^^^^^^^^
lxpanel-applet.vapi:80.28-80.41: error: The type name `Lxpanel.Button'
could not be found
public class MenuButton : Lxpanel.Button {
                          ^^^^^^^^^^^^^^
Compilation failed: 10 error(s), 0 warning(s)

Thank you guys!