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 d6c2531..2e5c527 100644
--- a/core/src/main/java/edu/umd/cs/piccolo/PCanvas.java
+++ b/core/src/main/java/edu/umd/cs/piccolo/PCanvas.java
@@ -602,8 +602,13 @@
         PDebug.startProcessingOutput();
 
         Graphics2D g2 = (Graphics2D) g.create();
-        g2.setColor(getBackground());
-        g2.fillRect(0, 0, getWidth(), getHeight());
+        
+		// support for non-opaque canvases
+        // see http://groups.google.com/group/piccolo2d-dev/browse_thread/thread/134e2792d3a54cf
+        if ( isOpaque() ) {
+            g2.setColor( getBackground() );
+            g2.fillRect( 0, 0, getWidth(), getHeight() );
+        }
 
         // create new paint context and set render quality to lowest common
         // denominator render quality.