non-working geany plugin

minimal.c

#include <geany/geanyplugin.h>

GeanyPlugin     *geany_plugin;
GeanyData       *geany_data;
GeanyFunctions  *geany_functions;

PLUGIN_VERSION_CHECK(211)
PLUGIN_SET_INFO("HelloWorld", "Just another tool to say hello world",
                "1.0", "John Doe <john.doe@example.org>");
static GtkWidget *main_menu_item = NULL;

static gboolean notify_cb(GObject obj, GeanyEditor *ed, SCNotification *nt, gpointer user_data);
PluginCallback plugin_callbacks[] =
{
    {"editor_notify", (GCallback)&notify_cb, TRUE,NULL},
    {NULL,NULL,FALSE,NULL}
};

static gboolean notify_cb(GObject obj, GeanyEditor *ed, SCNotification *nt, gpointer user_data)
{
    fprintf(stderr,"Code: %d\n",nt->nmhdr.code);
    return FALSE;
}

void plugin_init(GeanyData *data)
{
   return; 
}
void plugin_cleanup(void)
{
    return;
}