(defn show-graph
  "Show graph g in a JFrame with reversed edges if reversed is logically true."
  [g & [reversed]]
  (if (> (+ (vcount g) (ecount g)) 400)
    (do (println "Graph too big for visualizing!") nil)
    (let [img (-> (doto ^Tg2Dot (Tg2Dot.)
                    (.setGraph g)
                    (.setReversedEdges (if reversed true false)))
                  (.convertToGraphVizImageIcon
                   (-> (GraphVizProgram.)
                       (.outputFormat GraphVizOutputFormat/PNG))))
          label (JLabel. img)
          frame (JFrame. (str "Graph: " (id g)))]
      (doto frame
        (-> (.getContentPane)
            (.add (JScrollPane. label)))
        (.addKeyListener
         (proxy [KeyListener] []
           (keyPressed [e]
             (javax.swing.JOptionPane/showMessageDialog frame "I am displayed")
             (let [sf (case (.getKeyCode e)
                        KeyEvent/VK_PLUS  1.1
                        KeyEvent/VK_MINUS 0.9
                        0.5)
                   i (.getImage img)
                   si (.getScaledInstance (* sf (.getWidth i)) (* sf (.getHeight i)) 1)]
               (javax.swing.JOptionPane/showMessageDialog frame "I'm not displayed! Why???")
               (.setIcon label (ImageIcon. si))
               (.repaint frame)))
           (keyReleased [e])
           (keyTyped [e])))
        (.show)
        (.pack)))))