diff --git a/core/src/main/java/edu/umd/cs/piccolo/PCanvas.java b/core/src/main/java/edu/umd/cs/piccolo/PCanvas.java
index 92af3d2..34f5706 100644
--- a/core/src/main/java/edu/umd/cs/piccolo/PCanvas.java
+++ b/core/src/main/java/edu/umd/cs/piccolo/PCanvas.java
@@ -879,13 +879,13 @@
 
         final PBounds clippingRect = new PBounds(g.getClipBounds());
         clippingRect.expandNearestIntegerDimensions();
-        
+
         final PBounds originalCameraBounds = getCamera().getBounds();
         final PBounds layerBounds = getCamera().getUnionOfLayerFullBounds();
         getCamera().setBounds(layerBounds);
 
         final double clipRatio = clippingRect.getWidth() / clippingRect.getHeight();
-        final double nodeRatio = getWidth() / getHeight();
+        final double nodeRatio = ((double)getWidth()) / ((double)getHeight());
         final double scale;
         if (nodeRatio <= clipRatio) {
             scale = clippingRect.getHeight() / getCamera().getHeight();
diff --git a/core/src/main/java/edu/umd/cs/piccolo/PNode.java b/core/src/main/java/edu/umd/cs/piccolo/PNode.java
index ec6b9a4..2b1c9b6 100644
--- a/core/src/main/java/edu/umd/cs/piccolo/PNode.java
+++ b/core/src/main/java/edu/umd/cs/piccolo/PNode.java
@@ -875,7 +875,7 @@
             final byte[] ser = PObjectOutputStream.toByteArray(this);
             return new ObjectInputStream(new ByteArrayInputStream(ser)).readObject();
         }
-        catch (final IOException e) {
+        catch (final IOException e) {            
             return null;
         }
         catch (final ClassNotFoundException e) {
diff --git a/core/src/main/java/edu/umd/cs/piccolo/PRoot.java b/core/src/main/java/edu/umd/cs/piccolo/PRoot.java
index 40ce8cb..e9b6009 100644
--- a/core/src/main/java/edu/umd/cs/piccolo/PRoot.java
+++ b/core/src/main/java/edu/umd/cs/piccolo/PRoot.java
@@ -98,7 +98,7 @@
     /**
      * The singleton instance of the default input manager.
      */
-    private PInputManager defaultInputManager;
+    private transient PInputManager defaultInputManager;
 
     /** The Input Sources that are registered to this node. */
     private final transient List inputSources;
diff --git a/core/src/main/java/edu/umd/cs/piccolo/activities/PActivityScheduler.java b/core/src/main/java/edu/umd/cs/piccolo/activities/PActivityScheduler.java
index 7ad3e1d..2c85679 100644
--- a/core/src/main/java/edu/umd/cs/piccolo/activities/PActivityScheduler.java
+++ b/core/src/main/java/edu/umd/cs/piccolo/activities/PActivityScheduler.java
@@ -30,6 +30,7 @@
 
 import java.awt.event.ActionEvent;
 import java.awt.event.ActionListener;
+import java.io.Serializable;
 import java.util.ArrayList;
 import java.util.List;
 
@@ -52,11 +53,11 @@
  * @version 1.0
  * @author Jesse Grosjean
  */
-public class PActivityScheduler {
-
+public class PActivityScheduler implements Serializable {
+    private static final long serialVersionUID = 1L;
     private final PRoot root;
     private final List activities;
-    private Timer activityTimer;
+    private transient Timer activityTimer;
     private boolean activitiesChanged;
     private boolean animating;
     private final ArrayList processingActivities;
diff --git a/core/src/main/java/edu/umd/cs/piccolo/nodes/PHtmlView.java b/core/src/main/java/edu/umd/cs/piccolo/nodes/PHtmlView.java
index 9a56666..215355e 100644
--- a/core/src/main/java/edu/umd/cs/piccolo/nodes/PHtmlView.java
+++ b/core/src/main/java/edu/umd/cs/piccolo/nodes/PHtmlView.java
@@ -117,7 +117,7 @@
     private final JLabel label;
 
     /** Object that encapsulates the HTML rendering logic. */
-    private View htmlView;
+    private transient View htmlView;
 
     /**
      * Create an empty HTML text node with the default font and text color.
diff --git a/core/src/main/java/edu/umd/cs/piccolo/nodes/PText.java b/core/src/main/java/edu/umd/cs/piccolo/nodes/PText.java
index 2fcbcb3..1661e42 100644
--- a/core/src/main/java/edu/umd/cs/piccolo/nodes/PText.java
+++ b/core/src/main/java/edu/umd/cs/piccolo/nodes/PText.java
@@ -354,9 +354,10 @@
      * @param text text for this text node
      */
     public void setText(final String text) {
-        if (text == this.text) {
+        if ((text == null && this.text == null) || (text != null && text.equals(this.text))) {
             return;
         }
+
         final String oldText = this.text;
         this.text = text == null ? DEFAULT_TEXT : text;
         lines = null;
diff --git a/core/src/test/java/edu/umd/cs/piccolo/PerformanceTests.java b/core/src/test/java/edu/umd/cs/piccolo/PerformanceTests.java
index c8b8311..fcf16ae 100644
--- a/core/src/test/java/edu/umd/cs/piccolo/PerformanceTests.java
+++ b/core/src/test/java/edu/umd/cs/piccolo/PerformanceTests.java
@@ -222,7 +222,7 @@
         }
         log.endTest("Do fullIntersects test for " + NUMBER_NODES + " nodes");
     }
-
+    
     public void memorySizeOfNodes() {
         final PNode[] nodes = new PNode[NUMBER_NODES];
         Runtime.getRuntime().gc();