'Adds an element to the comparison.
:param element: the element to add.'

def add_element(self, element):

    self.elements.append(element)
    newlen = len(self.elements)
    self.showingPage = (newlen - 1)
    (title, realtext) = self._getElementText()
    if (newlen == 1):
        self.sensitive_all(True)
        self.comp.set_left_pane(title, realtext)
        self.leftElement = element
    else:
        self.delbut.set_sensitive(True)
    if (len([r[2] for r in self.elements if (r[2] is not None)]) >= 3):
        self.clusterbut.set_sensitive(True)
    self.comp.set_right_pane(title, realtext)
    self.pagesControl.activate(newlen)
    self.pagesControl.set_page(newlen)
