diff --git a/src/main/java/de/neemann/digital/draw/graphics/GraphicSwing.java b/src/main/java/de/neemann/digital/draw/graphics/GraphicSwing.java
index edbebecc4..017df3424 100644
--- a/src/main/java/de/neemann/digital/draw/graphics/GraphicSwing.java
+++ b/src/main/java/de/neemann/digital/draw/graphics/GraphicSwing.java
@@ -37,15 +37,14 @@ public class GraphicSwing implements Graphic {
     public void drawPolygon(Polygon p, Style style) {
         applyStyle(style);
         Path2D path = new GeneralPath();
-        for (int i=0;i<p.size();i++) {
+        for (int i = 0; i < p.size(); i++) {
             if (i == 0) {
                 path.moveTo(p.get(i).x, p.get(i).y);
             } else {
                 if (p.isBezierStart(i)) {
-                    path.curveTo(p.get(i).x, p.get(i).y, p.get(i+1).x, p.get(i+1).y, p.get(i+2).x, p.get(i+2).y);
-                    i+=2;
-                }
-                else
+                    path.curveTo(p.get(i).x, p.get(i).y, p.get(i + 1).x, p.get(i + 1).y, p.get(i + 2).x, p.get(i + 2).y);
+                    i += 2;
+                } else
                     path.lineTo(p.get(i).x, p.get(i).y);
             }
         }
diff --git a/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEAndShape.java b/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEAndShape.java
index 35ef8653e..4dd1c6056 100644
--- a/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEAndShape.java
+++ b/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEAndShape.java
@@ -24,8 +24,8 @@ public class IEEEAndShape extends IEEEGenericShape {
                 .add(1, SIZE * 2 + SIZE2)
                 .add(1, -SIZE2)
                 .add(SIZE + SIZE2, -SIZE2)
-                .add(new Vector(SIZE*2, -SIZE2),new Vector(SIZE*3, 0),new Vector(SIZE*3-1, SIZE))
-                .add(new Vector(SIZE*3-1, SIZE*2),new Vector(SIZE*2, SIZE*2+SIZE2),new Vector(SIZE+SIZE2, SIZE*2+SIZE2));
+                .add(new Vector(SIZE * 2, -SIZE2), new Vector(SIZE * 3, 0), new Vector(SIZE * 3 - 1, SIZE))
+                .add(new Vector(SIZE * 3 - 1, SIZE * 2), new Vector(SIZE * 2, SIZE * 2 + SIZE2), new Vector(SIZE + SIZE2, SIZE * 2 + SIZE2));
     }
 
     /**
diff --git a/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEENotShape.java b/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEENotShape.java
index 732451d03..2952e5407 100644
--- a/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEENotShape.java
+++ b/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEENotShape.java
@@ -1,8 +1,6 @@
 package de.neemann.digital.draw.shapes.ieee;
 
 import de.neemann.digital.core.Observer;
-import de.neemann.digital.core.element.ElementAttributes;
-import de.neemann.digital.core.element.Keys;
 import de.neemann.digital.core.element.PinDescription;
 import de.neemann.digital.draw.elements.IOState;
 import de.neemann.digital.draw.elements.Pin;
diff --git a/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEOrShape.java b/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEOrShape.java
index 70fc9ee4a..1fea4492d 100644
--- a/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEOrShape.java
+++ b/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEOrShape.java
@@ -28,12 +28,14 @@ public class IEEEOrShape extends IEEEGenericShape {
                 .add(SIZE2, -SIZE2)
                 .add(new Vector(SIZE, -SIZE2),
                         new Vector(SIZE * 2, 0),
-                        new Vector(SIZE * 3-1, SIZE))
+                        new Vector(SIZE * 3, SIZE))
                 .add(new Vector(SIZE * 2, SIZE * 2),
                         new Vector(SIZE, SIZE * 2 + SIZE2),
                         new Vector(SIZE2, SIZE * 2 + SIZE2));
     }
 
+    private final boolean center;
+
     /**
      * Creates a new instance
      *
@@ -43,10 +45,15 @@ public class IEEEOrShape extends IEEEGenericShape {
      */
     public IEEEOrShape(PinDescription[] inputs, PinDescription[] outputs, boolean invert) {
         super(inputs, outputs, invert);
+        center = (inputs.length & 1) != 0;
     }
 
     @Override
     protected void drawIEEE(Graphic graphic) {
+        graphic.drawLine(new Vector(0, 0), new Vector(4, 0), Style.WIRE);
+        graphic.drawLine(new Vector(0, SIZE * 2), new Vector(4, SIZE * 2), Style.WIRE);
+        if (center)
+            graphic.drawLine(new Vector(0, SIZE), new Vector(7, SIZE), Style.WIRE);
         graphic.drawPolygon(POLYGON, Style.NORMAL);
     }
 }
diff --git a/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEXOrShape.java b/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEXOrShape.java
index 394ed75b6..4d4894bc7 100644
--- a/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEXOrShape.java
+++ b/src/main/java/de/neemann/digital/draw/shapes/ieee/IEEEXOrShape.java
@@ -21,16 +21,16 @@ public class IEEEXOrShape extends IEEEGenericShape {
 
     private static Polygon createPoly() {
         return new Polygon(true)
-                .add(SIZE2+1, SIZE * 2 + SIZE2)
+                .add(SIZE2 + 1, SIZE * 2 + SIZE2)
                 .add(new Vector(SIZE, SIZE * 2),
                         new Vector(SIZE, 0),
-                        new Vector(SIZE2, -SIZE2))
+                        new Vector(SIZE2 + 1, -SIZE2))
                 .add(new Vector(SIZE, -SIZE2),
                         new Vector(SIZE * 2, 0),
-                        new Vector(SIZE * 3-1, SIZE))
+                        new Vector(SIZE * 3, SIZE))
                 .add(new Vector(SIZE * 2, SIZE * 2),
                         new Vector(SIZE, SIZE * 2 + SIZE2),
-                        new Vector(SIZE2+1, SIZE * 2 + SIZE2));
+                        new Vector(SIZE2 + 1, SIZE * 2 + SIZE2));
     }
 
     private static Polygon createPoly2() {
@@ -54,6 +54,8 @@ public class IEEEXOrShape extends IEEEGenericShape {
 
     @Override
     protected void drawIEEE(Graphic graphic) {
+        graphic.drawLine(new Vector(0, 0), new Vector(5 + SIZE2, 0), Style.WIRE);
+        graphic.drawLine(new Vector(0, SIZE * 2), new Vector(5 + SIZE2, SIZE * 2), Style.WIRE);
         graphic.drawPolygon(POLYGON, Style.NORMAL);
         graphic.drawPolygon(POLYGON2, Style.NORMAL);
     }
diff --git a/src/main/java/de/neemann/digital/gui/Main.java b/src/main/java/de/neemann/digital/gui/Main.java
index 2d6601962..618b9bee1 100644
--- a/src/main/java/de/neemann/digital/gui/Main.java
+++ b/src/main/java/de/neemann/digital/gui/Main.java
@@ -330,7 +330,7 @@ public class Main extends JFrame implements ClosingWindowListener.ConfirmSave, E
             @Override
             public void actionPerformed(ActionEvent e) {
                 if (new AttributeDialog(Main.this, Settings.SETTINGS_KEYS, Settings.getInstance().getAttributes()).showDialog())
-                    JOptionPane.showMessageDialog(Main.this,Lang.get("msg_restartNeeded"));;
+                    JOptionPane.showMessageDialog(Main.this, Lang.get("msg_restartNeeded"));
             }
         }.setToolTip(Lang.get("menu_editSettings_tt"));
 
diff --git a/src/main/java/de/neemann/digital/gui/Settings.java b/src/main/java/de/neemann/digital/gui/Settings.java
index 75ec25227..6c7084edd 100644
--- a/src/main/java/de/neemann/digital/gui/Settings.java
+++ b/src/main/java/de/neemann/digital/gui/Settings.java
@@ -16,7 +16,7 @@ import java.util.ArrayList;
  * <p/>
  * Created by Helmut.Neemann on 11.05.2016.
  */
-public class Settings implements AttributeListener {
+public final class Settings implements AttributeListener {
 
     /**
      * The list of supported attributes.
@@ -27,10 +27,8 @@ public class Settings implements AttributeListener {
         SETTINGS_KEYS.add(Keys.SETTINGS_IEEE_SHAPES);
     }
 
-    private static SettingsHolder settingsHolder = new SettingsHolder();
-
-    private static class SettingsHolder {
-        Settings INSTANCE = new Settings();
+    private static final class SettingsHolder {
+        static final Settings INSTANCE = new Settings();
     }
 
     /**
@@ -39,7 +37,7 @@ public class Settings implements AttributeListener {
      * @return the Settings
      */
     public static Settings getInstance() {
-        return settingsHolder.INSTANCE;
+        return SettingsHolder.INSTANCE;
     }
 
     private ElementAttributes attributes;