Now you can toggle the state, and it isn't spazzy!

src/Render.java

@@ -31,6 +31,7 @@ public class Render extends Canvas implements Runnable, MouseListener,
     private JFrame _frame;
     private JButton pauseButton;
     private Random random = new Random();
+    private int _lastX, _lastY;
 
     public Render(int width, int height, Grid g, String[] rules) {
         addMouseListener(this);
@@ -47,6 +48,7 @@ public class Render extends Canvas implements Runnable, MouseListener,
         _pixels = ((DataBufferInt) _image.getRaster().getDataBuffer()).getData();
         _lastTick = 0;
         _rules = rules;
+        _lastX = _lastY = -1;
         fps_now = 15;
         setFrame();
     }
@@ -215,14 +217,32 @@ public class Render extends Canvas implements Runnable, MouseListener,
         int states = Goldfish.getMaxStates(rule) - 1;
         if (e.getX() < 0 || e.getY() < 0 || e.getX() / scale > width || e.getY() / scale > height)
             return;
-        _grid.getPatch(e.getX() / scale, e.getY() / scale).setState(states);
+        if (e.getX()/scale != _lastX && e.getY()/scale != _lastY) {
+            _lastX = e.getX()/scale;
+            _lastY = e.getY()/scale;
+            Patch p = _grid.getPatch(_lastX, _lastY);
+            if (p.getState() == states) {
+                p.setState(0);
+            } else {
+                _grid.getPatch(e.getX() / scale, e.getY() / scale).setState(states);
+            }
+        }
         e.consume();
     }
 
     @Override
     public void mouseClicked(MouseEvent e) {
         int states = Goldfish.getMaxStates(rule) - 1;
-        _grid.getPatch(e.getX() / scale, e.getY() / scale).setState(states);
+        if (e.getX()/scale != _lastX && e.getY()/scale != _lastY) {
+            _lastX = e.getX()/scale;
+            _lastY = e.getY()/scale;
+            Patch p = _grid.getPatch(_lastX, _lastY);
+            if (p.getState() == states) {
+                p.setState(0);
+            } else {
+                _grid.getPatch(e.getX() / scale, e.getY() / scale).setState(states);
+            }
+        }
         e.consume();
     }
 
@@ -237,12 +257,22 @@ public class Render extends Canvas implements Runnable, MouseListener,
     @Override
     public void mousePressed(MouseEvent e) {
         int states = Goldfish.getMaxStates(rule) - 1;
-        _grid.getPatch(e.getX() / scale, e.getY() / scale).setState(states);
+        if (e.getX()/scale != _lastX && e.getY()/scale != _lastY) {
+            _lastX = e.getX()/scale;
+            _lastY = e.getY()/scale;
+            Patch p = _grid.getPatch(_lastX, _lastY);
+            if (p.getState() == states) {
+                p.setState(0);
+            } else {
+                _grid.getPatch(e.getX() / scale, e.getY() / scale).setState(states);
+            }
+        }
         e.consume();
     }
 
     @Override
     public void mouseReleased(MouseEvent e) {
+        _lastX = _lastY = -1;
     }
 
     @Override