'Shows an almost empty panel when there\'s no configuration.
:param title: the title to show in the top (optional)
:param title: the long description for the plugin to show in the top (optional)
:param label: a message to the middle of the panel (optional).
When it does not receive nothing, the panel is clean.'

def clear(self, title=None, longdesc='', label=''):

    vbox = gtk.VBox()
    vbox.set_spacing(5)
    if (title is not None):
        titl = gtk.Label()
        titl.set_markup(title)
        titl.set_alignment(0.0, 0.5)
        titl.show()
        vbox.pack_start(titl)
    if (longdesc is not None):
        long_label = gtk.Label()
        long_label.set_text(longdesc)
        long_label.set_alignment(0.0, 0.5)
        long_label.show()
        vbox.pack_start(long_label)
    labl = gtk.Label(label)
    labl.show()
    vbox.pack_start(labl)
    vbox.show()
    if (self.widg is not None):
        self.remove(self.widg)
    self.add(vbox)
    self.widg = vbox
