Configuring

In init_view_plugin we affected something to vpd->configure. It is a function defined as : mstatic GtkWidget* configure(ViewPluginData *vpd); It is used in the 'configure' box inside Gaby. Since you don't have anything to configure you may simply type (or affect NULL to the variable :
mstatic GtkWidget* configure(ViewPluginData *vpd)
{
        return NULL;
}