'Make an xterm when a button is pressed.'

def iperf(self, _ignore=None):

    if ((self.selection is None) or (self.net is None) or (self.selection not in self.itemToWidget)):
        return
    name = self.itemToWidget[self.selection]['text']
    if (name not in self.net.nameToNode):
        return
    self.net.nameToNode[name].cmd('iperf    -s    -p    5001    &')
