Index: src/org/eclipse/gmf/runtime/diagram/ui/editparts/DiagramRootEditPart.java
===================================================================
RCS file: /home/technology/org.eclipse.gmf/plugins/org.eclipse.gmf.runtime.diagram.ui/src/org/eclipse/gmf/runtime/diagram/ui/editparts/DiagramRootEditPart.java,v
retrieving revision 1.6
diff -u -r1.6 DiagramRootEditPart.java
--- src/org/eclipse/gmf/runtime/diagram/ui/editparts/DiagramRootEditPart.java	28 Oct 2005 14:29:38 -0000	1.6
+++ src/org/eclipse/gmf/runtime/diagram/ui/editparts/DiagramRootEditPart.java	2 Nov 2005 16:32:35 -0000
@@ -176,7 +176,7 @@
         layers.add(new FreeformLayer(), DECORATION_UNPRINTABLE_LAYER);
         return layers;
     }
-   
+    
     /**
      * Creates the <code>ScalableFreeformLayeredPane</code>.
 	 * @return the new <code>ScalableFreeformLayeredPane</code>
@@ -438,11 +438,15 @@
 	 * @param rulerUnits
 	 */
 	private void setRulers(int rulerUnits) {
-		if( verticalRuler != null ) {
-			verticalRuler.setUnit( rulerUnits );
+		if( getVerticalRuler() != null ) {
+			getVerticalRuler().setUnit( rulerUnits );
+		} else {
+			setVerticalRuler(new DiagramRuler(false, rulerUnits, null));
 		}
-		if( horizontalRuler != null ) {
-			horizontalRuler.setUnit( rulerUnits );
+		if( getHorizontalRuler() != null ) {
+			getHorizontalRuler().setUnit( rulerUnits );
+		} else {
+			setHorizontalRuler(new DiagramRuler(true, rulerUnits, null));			
 		}
 	}
 
@@ -477,6 +481,17 @@
 			((org.eclipse.gmf.runtime.draw2d.ui.internal.graphics.ScalableFreeformLayeredPane) layers).setAntiAlias(antiAlias);
 	}
 
+	/**
+	 * Refreshes ruler units on the diagram
+	 */
+	protected void refreshRulerUnits() {
+		IPreferenceStore preferenceStore =
+			(IPreferenceStore) getPreferencesHint().getPreferenceStore();
+		int rulerUnits = preferenceStore.getInt(
+			IPreferenceConstants.PREF_RULER_UNITS);
+		setRulers(rulerUnits);
+	}
+
 	
 	/**
 	 * This is a workspace property request.  It does not use a <code>Command</code>
@@ -503,6 +518,8 @@
 		
 		refreshEnableAntiAlias();
 		
+		refreshRulerUnits();
+		
 		if (pane instanceof ZoomListener) {
 			getZoomManager().addZoomListener((ZoomListener)pane);
 		}
@@ -577,7 +594,7 @@
 	public PreferencesHint getPreferencesHint() {
 		return preferencesHint;
 	}
-	
+
 	/**
 	 * Override this if the Editor wishes to support a coordinate system other then the default 
 	 * (usually HiMetric coordinates).  
@@ -587,5 +604,24 @@
 	public IMapMode getMapMode() {
 		return MapModeTypes.DEFAULT_MM;
 	}
+	
+	public DiagramRuler getHorizontalRuler() {
+		return horizontalRuler;
+	}
+
+	
+	private void setHorizontalRuler(DiagramRuler horizontalRuler) {
+		this.horizontalRuler = horizontalRuler;
+	}
+
+	
+	public DiagramRuler getVerticalRuler() {
+		return verticalRuler;
+	}
+
+	
+	private void setVerticalRuler(DiagramRuler verticalRuler) {
+		this.verticalRuler = verticalRuler;
+	}
 
 }
Index: src/org/eclipse/gmf/runtime/diagram/ui/internal/ruler/DiagramRuler.java
===================================================================
RCS file: /home/technology/org.eclipse.gmf/plugins/org.eclipse.gmf.runtime.diagram.ui/src/org/eclipse/gmf/runtime/diagram/ui/internal/ruler/DiagramRuler.java,v
retrieving revision 1.5
diff -u -r1.5 DiagramRuler.java
--- src/org/eclipse/gmf/runtime/diagram/ui/internal/ruler/DiagramRuler.java	22 Sep 2005 15:42:19 -0000	1.5
+++ src/org/eclipse/gmf/runtime/diagram/ui/internal/ruler/DiagramRuler.java	2 Nov 2005 16:32:35 -0000
@@ -88,4 +88,9 @@
 		PresentationListener.getInstance().removeNotificationListener(getGuideStyle(),listener);
 
 	}
+
+	
+	public void setGuideStyle(GuideStyle guideStyle) {
+		this.guideStyle = guideStyle;
+	}
 }
Index: src/org/eclipse/gmf/runtime/diagram/ui/parts/DiagramEditor.java
===================================================================
RCS file: /home/technology/org.eclipse.gmf/plugins/org.eclipse.gmf.runtime.diagram.ui/src/org/eclipse/gmf/runtime/diagram/ui/parts/DiagramEditor.java,v
retrieving revision 1.6
diff -u -r1.6 DiagramEditor.java
--- src/org/eclipse/gmf/runtime/diagram/ui/parts/DiagramEditor.java	14 Oct 2005 20:50:55 -0000	1.6
+++ src/org/eclipse/gmf/runtime/diagram/ui/parts/DiagramEditor.java	2 Nov 2005 16:32:36 -0000
@@ -720,10 +720,13 @@
 	 * @return the zoom manager
 	 */
 	protected ZoomManager getZoomManager() {
-		return ((DiagramRootEditPart) getGraphicalViewer().getRootEditPart())
-			.getZoomManager();
+		return ((DiagramRootEditPart) getRootEditPart()).getZoomManager();
 	}
 
+	private RootEditPart getRootEditPart() {
+		return getGraphicalViewer().getRootEditPart();		
+	}
+	
 	/**
 	 * Convenience method to access the command manager associated with my
 	 * action manager. This command manager is used by my edit domain's 
@@ -925,8 +928,6 @@
 		}
 	}
 
-	IPreferenceStore pluginStore = DiagramUIPlugin.getInstance()
-		.getPreferenceStore();
 
 	/**
 	 * Initializes the viewer's state from the workspace preference store.
@@ -953,7 +954,7 @@
 		}
 
 		// Get the Ruler Units properties
-		int rulerUnits = pluginStore
+		int rulerUnits = ((IPreferenceStore) ((DiagramRootEditPart) getRootEditPart()).getPreferencesHint().getPreferenceStore())
 			.getInt(IPreferenceConstants.PREF_RULER_UNITS);
 
 		// Get the Guide Style
@@ -964,8 +965,9 @@
 		if (guideStyle != null) {
 
 			// Set the Vertical Ruler properties
-			DiagramRuler verticalRuler = new DiagramRuler(false, rulerUnits,
-				guideStyle);
+			DiagramRuler verticalRuler = ((DiagramRootEditPart) getRootEditPart()).getVerticalRuler();
+			verticalRuler.setGuideStyle(guideStyle);
+			verticalRuler.setUnit(rulerUnits);
 			DiagramRulerProvider vertProvider = new DiagramRulerProvider(
 				verticalRuler);
 			vertProvider.init();
@@ -973,14 +975,15 @@
 				RulerProvider.PROPERTY_VERTICAL_RULER, vertProvider);
 	
 			// Set the Horizontal Ruler properties
-			DiagramRuler horizontalRuler = new DiagramRuler(true, rulerUnits,
-				guideStyle);
+			DiagramRuler horizontalRuler = ((DiagramRootEditPart) getRootEditPart()).getHorizontalRuler();
+			horizontalRuler.setGuideStyle(guideStyle);
+			horizontalRuler.setUnit(rulerUnits);
 			DiagramRulerProvider horzProvider = new DiagramRulerProvider(
 				horizontalRuler);
 			horzProvider.init();
 			getDiagramGraphicalViewer().setProperty(
 				RulerProvider.PROPERTY_HORIZONTAL_RULER, horzProvider);
-	
+			
 			// Show/Hide Rulers
 			getDiagramGraphicalViewer().setProperty(
 				RulerProvider.PROPERTY_RULER_VISIBILITY,