Index: src/org/jbpm/gd/common/editor/GraphicalViewer.java
===================================================================
--- src/org/jbpm/gd/common/editor/GraphicalViewer.java	(revision 32289)
+++ src/org/jbpm/gd/common/editor/GraphicalViewer.java	(working copy)
@@ -33,6 +33,7 @@
 import org.eclipse.jface.viewers.ISelectionProvider;
 import org.eclipse.swt.graphics.Rectangle;
 import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Display;
 import org.eclipse.ui.views.properties.IPropertySheetPage;
 import org.jbpm.gd.jpdl.Constants;
 
@@ -82,7 +83,7 @@
 	
 	protected void fireSelectionChanged() {
 		super.fireSelectionChanged();
-		if (getSelection() != null) {
+		if (getSelection() != null && editor.getPropertySheetPage().getControl() != null) {
 			editor.getPropertySheetPage().selectionChanged(editor, getSelection());
 		}
 	}