Unregisters the view at the given name.  If the window option is \
        supplied then the unregisterFromWindow method will be called for the \
        inputed class.
        
        :param          cls    | <subclass of XView>    
                        window | <QMainWindow> || <QDialog> || None
        
        :return     <bool> changed

def unregisterViewType(self, cls, window=None):
        """
        Unregisters the view at the given name.  If the window option is \
        supplied then the unregisterFromWindow method will be called for the \
        inputed class.
        
        :param          cls    | <subclass of XView>    
                        window | <QMainWindow> || <QDialog> || None
        
        :return     <bool> changed
        """
        if ( cls in self._viewTypes ):
            self._viewTypes.remove(cls)
            
            if ( window ):
                cls.unregisterFromWindow(window)
                
            return True
        return False