diff --git a/core/org.eclipse.cdt.core.tests/misc/org/eclipse/cdt/core/cdescriptor/tests/CDescriptorOldTests.java b/core/org.eclipse.cdt.core.tests/misc/org/eclipse/cdt/core/cdescriptor/tests/CDescriptorOldTests.java
new file mode 100644
index 00000000000..90a7afefa20
--- /dev/null
+++ b/core/org.eclipse.cdt.core.tests/misc/org/eclipse/cdt/core/cdescriptor/tests/CDescriptorOldTests.java
@@ -0,0 +1,404 @@
+/**********************************************************************
+ * Copyright (c) 2004, 2008 QNX Software Systems Ltd and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     QNX Software Systems Ltd - initial API and implementation
+ *     Anton Leherbauer (Wind River Systems)
+ *     James Blackburn (Broadcom Corp)
+ ***********************************************************************/
+
+package org.eclipse.cdt.core.cdescriptor.tests;
+
+import junit.extensions.TestSetup;
+import junit.framework.Assert;
+import junit.framework.Test;
+import junit.framework.TestCase;
+import junit.framework.TestSuite;
+
+import org.eclipse.cdt.core.CCorePlugin;
+import org.eclipse.cdt.core.CDescriptorEvent;
+import org.eclipse.cdt.core.CProjectNature;
+import org.eclipse.cdt.core.ICDescriptor;
+import org.eclipse.cdt.core.ICDescriptorListener;
+import org.eclipse.cdt.core.ICDescriptorOperation;
+import org.eclipse.cdt.core.ICExtensionReference;
+import org.eclipse.cdt.core.ICOwnerInfo;
+import org.eclipse.cdt.core.testplugin.CTestPlugin;
+import org.eclipse.cdt.internal.core.pdom.PDOMManager;
+import org.eclipse.core.resources.IProject;
+import org.eclipse.core.resources.IProjectDescription;
+import org.eclipse.core.resources.IResource;
+import org.eclipse.core.resources.IWorkspaceRoot;
+import org.eclipse.core.resources.IWorkspaceRunnable;
+import org.eclipse.core.runtime.CoreException;
+import org.eclipse.core.runtime.IProgressMonitor;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+
+/**
+ * This class exists because the tests in CDescriptorTests
+ * are not fixed.
+ * This class corresponds to the version of 
+ * CDescrptorTests before the changes made in cdt.core 5.1
+ * (CVS version 1.12)
+ */
+public class CDescriptorOldTests extends TestCase {
+
+	static String projectId = CTestPlugin.PLUGIN_ID + ".TestProject";
+	static IProject fProject;
+	static CDescriptorListener listener = new CDescriptorListener();
+	static CDescriptorEvent fLastEvent;
+
+	/**
+	 * Constructor for CDescriptorTest.
+	 * 
+	 * @param name
+	 */
+	public CDescriptorOldTests(String name) {
+		super(name);
+	}
+
+	public static Test suite() {
+		TestSuite suite = new TestSuite(CDescriptorOldTests.class.getName());
+
+		suite.addTest(new CDescriptorOldTests("testDescriptorCreation"));
+		suite.addTest(new CDescriptorOldTests("testDescriptorOwner"));
+		suite.addTest(new CDescriptorOldTests("testExtensionCreation"));
+		suite.addTest(new CDescriptorOldTests("testExtensionGet"));
+		suite.addTest(new CDescriptorOldTests("testExtensionData"));
+		suite.addTest(new CDescriptorOldTests("testExtensionRemove"));
+		suite.addTest(new CDescriptorOldTests("testProjectDataCreate"));
+		suite.addTest(new CDescriptorOldTests("testProjectDataDelete"));
+		suite.addTest(new CDescriptorOldTests("testConcurrentDescriptorCreation"));
+		suite.addTest(new CDescriptorOldTests("testConcurrentDescriptorCreation2"));
+		suite.addTest(new CDescriptorOldTests("testDeadlockDuringProjectCreation"));
+		suite.addTest(new CDescriptorOldTests("testProjectStorageDelete"));
+		
+		TestSetup wrapper = new TestSetup(suite) {
+
+			@Override
+			protected void setUp() throws Exception {
+				oneTimeSetUp();
+			}
+
+			@Override
+			protected void tearDown() throws Exception {
+				oneTimeTearDown();
+			}
+
+		};
+		return wrapper;
+	}
+
+	private static void addNatureToProject(IProject proj, String natureId, IProgressMonitor monitor) throws CoreException {
+		IProjectDescription description = proj.getDescription();
+		String[] prevNatures = description.getNatureIds();
+		String[] newNatures = new String[prevNatures.length + 1];
+		System.arraycopy(prevNatures, 0, newNatures, 0, prevNatures.length);
+		newNatures[prevNatures.length] = natureId;
+		description.setNatureIds(newNatures);
+		proj.setDescription(description, monitor);
+	}
+
+	static public class CDescriptorListener implements ICDescriptorListener {
+
+		public void descriptorChanged(CDescriptorEvent event) {
+			fLastEvent = event;
+		}
+	}
+
+	static void oneTimeSetUp() throws Exception {
+		CTestPlugin.getWorkspace().run(new IWorkspaceRunnable() {
+
+			public void run(IProgressMonitor monitor) throws CoreException {
+				IWorkspaceRoot root = CTestPlugin.getWorkspace().getRoot();
+				IProject project = root.getProject("testDescriptorProject");
+				if (!project.exists()) {
+					project.create(null);
+				} else {
+					project.refreshLocal(IResource.DEPTH_INFINITE, null);
+				}
+				if (!project.isOpen()) {
+					project.open(null);
+				}
+				CCorePlugin.getDefault().getCDescriptorManager().addDescriptorListener(listener);
+				if (!project.hasNature(CProjectNature.C_NATURE_ID)) {
+					addNatureToProject(project, CProjectNature.C_NATURE_ID, null);
+				}
+				fProject = project;
+			}
+		}, null);
+	}
+
+	static void oneTimeTearDown() throws Exception {
+		fProject.delete(true, true, null);
+	}
+
+	public void testDescriptorCreation() throws Exception {
+		CTestPlugin.getWorkspace().run(new IWorkspaceRunnable() {
+
+			public void run(IProgressMonitor monitor) throws CoreException {
+				CCorePlugin.getDefault().mapCProjectOwner(fProject, projectId, false);
+			}
+		}, null);
+		ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+
+		Assert.assertNotNull(fLastEvent);
+		Assert.assertEquals(fLastEvent.getDescriptor(), desc);
+		Assert.assertEquals(fLastEvent.getType(), CDescriptorEvent.CDTPROJECT_ADDED);
+		Assert.assertEquals(fLastEvent.getFlags(), 0);
+		fLastEvent = null;
+
+		Assert.assertEquals(fProject, desc.getProject());
+		Assert.assertEquals("*", desc.getPlatform());
+	}
+
+	// https://bugs.eclipse.org/bugs/show_bug.cgi?id=185930
+	public void testConcurrentDescriptorCreation() throws Exception {
+		fProject.close(null);
+		fProject.open(null);
+		Thread t= new Thread() {
+			@Override
+			public void run() {
+				try {
+					CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+				} catch (CoreException exc) {
+				}
+			}
+		};
+		t.start();
+		ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+		t.join();
+		
+		Element data = desc.getProjectData("testElement0");
+		data.appendChild(data.getOwnerDocument().createElement("test"));
+		desc.saveProjectData();
+		fLastEvent = null;
+ 	}
+
+	// https://bugs.eclipse.org/bugs/show_bug.cgi?id=185930
+	// https://bugs.eclipse.org/bugs/show_bug.cgi?id=193503
+	// https://bugs.eclipse.org/bugs/show_bug.cgi?id=196118
+	public void testConcurrentDescriptorCreation2() throws Exception {
+		int lastLength = 0;
+		for (int i=0; i<200; ++i) {
+			final int indexi = i;
+			PDOMManager pdomMgr= (PDOMManager)CCorePlugin.getIndexManager();
+			pdomMgr.shutdown();
+			fProject.close(null);
+			fProject.open(null);
+			pdomMgr.startup().schedule();
+			ICDescriptor desc= CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+			if (lastLength == 0)
+				lastLength = countChildElements(desc.getProjectData("testElement"));
+			final Throwable[] exception= new Throwable[10];
+			Thread[] threads= new Thread[10];
+			for (int j = 0; j < 10; j++) {
+				final int indexj = j;
+				Thread t= new Thread() {
+					@Override
+					public void run() {
+						try {
+							ICDescriptorOperation operation= new ICDescriptorOperation() {
+								public void execute(ICDescriptor descriptor, IProgressMonitor monitor) throws CoreException {
+									assertFalse(descriptor.getConfigurationDescription().isReadOnly());
+									Element data = descriptor.getProjectData("testElement");
+									String test = "test"+(indexi*10 + indexj);
+									data.appendChild(data.getOwnerDocument().createElement(test));
+									assertFalse(descriptor.getConfigurationDescription().isReadOnly());
+									// BUG196118 the model cached in memory doesn't reflect the contents of .cproject
+									//
+									// descriptor.saveProjectData() doesn't actually save despite what the API says
+									// see CConfigBasedDescriptor.fApplyOnChange
+//									((CConfigBasedDescriptor)descriptor).apply(false);
+//									System.out.println("Saved " + test);
+								}};
+								CCorePlugin.getDefault().getCDescriptorManager().runDescriptorOperation(fProject, operation, null);
+								ICDescriptor descriptor = CCorePlugin.getDefault().getCDescriptorManager().getDescriptor(fProject);
+								// perform apply outside descriptor operation to avoid deadlock - http://bugs.eclipse.org/241288 
+								descriptor.saveProjectData();
+						} catch (Throwable exc) {
+							exception[indexj]= exc;
+							exc.printStackTrace();
+						}
+					}
+				};
+				t.start();
+				threads[j] = t;
+			}
+			for (int j = 0; j < threads.length; j++) {
+				if (threads[j] != null) {
+					threads[j].join();
+				}
+				assertNull("Exception occurred: "+exception[j], exception[j]);
+			}
+			desc= CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+			int lengthAfter = countChildElements(desc.getProjectData("testElement"));
+			lastLength += threads.length; // Update last lengths to what we expect
+			assertEquals("Iteration count: " + i, lastLength, lengthAfter);
+
+			fLastEvent = null;
+		}
+	}
+
+	/**
+	 * Count the number of Node.ELEMENT_NODE elements which are a 
+	 * direct descendent of the parent Element.
+	 * Other nodes (e.g. Text) are ignored
+	 * @param parent
+	 * @return
+	 */
+	private int countChildElements(Element parent) {
+		int numElements = 0;
+		NodeList childNodes = parent.getChildNodes();
+		for (int k = 0 ; k < childNodes.getLength() ; k++)
+			if (childNodes.item(k).getNodeType() == Node.ELEMENT_NODE)
+				numElements ++;
+		return numElements;
+	}
+
+	public void testDeadlockDuringProjectCreation() throws Exception {
+		for (int i=0; i < 10; ++i) {
+			oneTimeTearDown();
+			oneTimeSetUp();
+			Thread t= new Thread() {
+				@Override
+				public void run() {
+					try {
+						ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+						Element data = desc.getProjectData("testElement0");
+						data.appendChild(data.getOwnerDocument().createElement("test"));
+						desc.saveProjectData();
+					} catch (CoreException exc) {
+					}
+				}
+			};
+			t.start();
+
+			ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+			Element data = desc.getProjectData("testElement0");
+			data.appendChild(data.getOwnerDocument().createElement("test"));
+			desc.saveProjectData();
+			t.join();
+			
+			fLastEvent = null;
+		}
+ 	}
+
+	public void testDescriptorOwner() throws Exception {
+		ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+		ICOwnerInfo owner = desc.getProjectOwner();
+		Assert.assertEquals(projectId, owner.getID());
+		Assert.assertEquals("*", owner.getPlatform());
+		Assert.assertEquals("C/C++ Test Project", owner.getName());
+	}
+
+	public void testDescriptorConversion() {
+
+	}
+
+	public void testExtensionCreation() throws Exception {
+		ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+		ICExtensionReference extRef = desc.create("org.eclipse.cdt.testextension", "org.eclipse.cdt.testextensionID");
+
+		Assert.assertNotNull(fLastEvent);
+		Assert.assertEquals(fLastEvent.getDescriptor(), desc);
+		Assert.assertEquals(fLastEvent.getType(), CDescriptorEvent.CDTPROJECT_CHANGED);
+		Assert.assertEquals(fLastEvent.getFlags(), CDescriptorEvent.EXTENSION_CHANGED);
+		fLastEvent = null;
+
+		Assert.assertEquals("org.eclipse.cdt.testextension", extRef.getExtension());
+		Assert.assertEquals("org.eclipse.cdt.testextensionID", extRef.getID());
+	}
+
+	public void testExtensionGet() throws Exception {
+		ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+		ICExtensionReference extRef[] = desc.get("org.eclipse.cdt.testextension");
+
+		Assert.assertEquals("org.eclipse.cdt.testextension", extRef[0].getExtension());
+		Assert.assertEquals("org.eclipse.cdt.testextensionID", extRef[0].getID());
+	}
+
+	public void testExtensionData() throws Exception {
+		ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+		ICExtensionReference extRef[] = desc.get("org.eclipse.cdt.testextension");
+		extRef[0].setExtensionData("testKey", "testValue");
+
+		Assert.assertNotNull(fLastEvent);
+		Assert.assertEquals(fLastEvent.getDescriptor(), desc);
+		Assert.assertEquals(fLastEvent.getType(), CDescriptorEvent.CDTPROJECT_CHANGED);
+		Assert.assertEquals(fLastEvent.getFlags(), 0);
+		fLastEvent = null;
+
+		Assert.assertEquals("testValue", extRef[0].getExtensionData("testKey"));
+		extRef[0].setExtensionData("testKey", null);
+		Assert.assertEquals(null, extRef[0].getExtensionData("testKey"));
+	}
+
+	public void testExtensionRemove() throws Exception {
+		ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+		ICExtensionReference extRef[] = desc.get("org.eclipse.cdt.testextension");
+		desc.remove(extRef[0]);
+
+		Assert.assertNotNull(fLastEvent);
+		Assert.assertEquals(fLastEvent.getDescriptor(), desc);
+		Assert.assertEquals(fLastEvent.getType(), CDescriptorEvent.CDTPROJECT_CHANGED);
+		Assert.assertEquals(fLastEvent.getFlags(), CDescriptorEvent.EXTENSION_CHANGED);
+		fLastEvent = null;
+
+	}
+
+	public void testProjectDataCreate() throws Exception {
+		ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+		Element data = desc.getProjectData("testElement");
+		data.appendChild(data.getOwnerDocument().createElement("test"));
+		desc.saveProjectData();
+
+		Assert.assertNotNull(fLastEvent);
+		Assert.assertEquals(fLastEvent.getDescriptor(), desc);
+		Assert.assertEquals(fLastEvent.getType(), CDescriptorEvent.CDTPROJECT_CHANGED);
+		Assert.assertEquals(fLastEvent.getFlags(), 0);
+		fLastEvent = null;
+	}
+
+	public void testProjectDataDelete() throws Exception {
+		ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+		Element data = desc.getProjectData("testElement");
+		NodeList list = data.getElementsByTagName("test");
+		Assert.assertEquals(1, list.getLength());
+		data.removeChild(data.getFirstChild());
+		desc.saveProjectData();
+
+		Assert.assertNotNull(fLastEvent);
+		Assert.assertEquals(fLastEvent.getDescriptor(), desc);
+		Assert.assertEquals(fLastEvent.getType(), CDescriptorEvent.CDTPROJECT_CHANGED);
+		Assert.assertEquals(fLastEvent.getFlags(), 0);
+		fLastEvent = null;
+	}
+
+	public void testProjectStorageDelete() throws Exception {
+		// 1st Add an item
+		ICDescriptor desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+		Element data = desc.getProjectData("testElement");
+		data.appendChild(data.getOwnerDocument().createElement("test"));
+		desc.saveProjectData();
+
+		// 2nd remove the storage element containing it
+		desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+		data = desc.getProjectData("testElement");
+		data.getParentNode().removeChild(data);
+		desc.saveProjectData();
+
+		// 3rd check the item no longer exists
+		desc = CCorePlugin.getDefault().getCProjectDescription(fProject, true);
+		data = desc.getProjectData("testElement");
+		assertTrue(data.getChildNodes().getLength() == 0);		
+		fLastEvent = null;
+	}
+
+}
diff --git a/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/suite/AutomatedIntegrationSuite.java b/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/suite/AutomatedIntegrationSuite.java
index 0cd996bc3b0..367770d9ea4 100644
--- a/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/suite/AutomatedIntegrationSuite.java
+++ b/core/org.eclipse.cdt.core.tests/suite/org/eclipse/cdt/core/suite/AutomatedIntegrationSuite.java
@@ -16,6 +16,7 @@ import junit.framework.Test;
 import junit.framework.TestSuite;
 
 import org.eclipse.cdt.core.cdescriptor.tests.CDescriptorTests;
+import org.eclipse.cdt.core.cdescriptor.tests.CDescriptorOldTests;
 import org.eclipse.cdt.core.internal.errorparsers.tests.ErrorParserTests;
 import org.eclipse.cdt.core.internal.tests.PositionTrackerTests;
 import org.eclipse.cdt.core.internal.tests.ResourceLookupTests;
@@ -56,6 +57,7 @@ public class AutomatedIntegrationSuite extends TestSuite {
 		
 		// Add all success tests
 		suite.addTest(CDescriptorTests.suite());
+		suite.addTest(CDescriptorOldTests.suite());
 		suite.addTest(ErrorParserTests.suite());
 		suite.addTest(ParserTestSuite.suite());
 		suite.addTest(AllCoreTests.suite());
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICProjectDescriptionManager.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICProjectDescriptionManager.java
index c743ee791a0..26e48178015 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICProjectDescriptionManager.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICProjectDescriptionManager.java
@@ -17,6 +17,8 @@ import org.eclipse.core.runtime.IProgressMonitor;
 
 /**
  * This interface represents the manager of CDT Project descriptions.
+ * @noextend This interface is not intended to be extended by clients.
+ * @noimplement This interface is not intended to be implemented by clients.
  */
 public interface ICProjectDescriptionManager {
 	/*
@@ -42,6 +44,7 @@ public interface ICProjectDescriptionManager {
 	/** 
 	 * Flag indicating that a new empty ICProjectDescription should be created and returned 
 	 * (irrespective of whether one already exists) 
+	 * @since 5.1
 	 */
 	public static final int GET_EMPTY_PROJECT_DESCRIPTION = 1 << 4;
 	/**
@@ -49,6 +52,7 @@ public interface ICProjectDescriptionManager {
 	 * i.e. a description should be returned irrespective of whether one already exists.
 	 * If the project already has a description and !{@link #GET_EMPTY_PROJECT_DESCRIPTION}
 	 * the existing description will be returned, otherwise a new description is returned
+	 * @since 5.1
 	 */
 	public static final int GET_CREATE_DESCRIPTION = 1 << 5;
 	/** 
@@ -58,6 +62,7 @@ public interface ICProjectDescriptionManager {
 	 * 
  	 * @see #GET_CREATE_DESCRIPTION
 	 * @see ICProjectDescription#isCdtProjectCreating() 
+	 * @since 5.1
 	 */
 	public static final int PROJECT_CREATING = 1 << 6;
 
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICSettingsStorage.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICSettingsStorage.java
index 1f69fd38f6a..c958c61f6c5 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICSettingsStorage.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICSettingsStorage.java
@@ -11,8 +11,6 @@
  *******************************************************************************/
 package org.eclipse.cdt.core.settings.model;
 
-import java.util.Map;
-
 import org.eclipse.cdt.core.ICDescriptor;
 import org.eclipse.cdt.core.settings.model.extension.CConfigurationData;
 import org.eclipse.cdt.core.settings.model.extension.CConfigurationDataProvider;
@@ -44,6 +42,9 @@ import org.eclipse.core.runtime.IProgressMonitor;
  * @see ICProjectDescription
  * @see ICConfigurationDescription
  * @see ICDescriptor
+ * 
+ * @noextend This interface is not intended to be extended by clients.
+ * @noimplement This interface is not intended to be implemented by clients.
  */
 public interface ICSettingsStorage {
 	/**
@@ -80,18 +81,21 @@ public interface ICSettingsStorage {
 	 * @param el ICStorageElement to be imported
 	 * @return ICStorageElement representing the imported storage
 	 * @throws UnsupportedOperationException
+	 * @since 5.1
 	 */
 	public ICStorageElement importStorage(String id, ICStorageElement el) throws UnsupportedOperationException, CoreException;
 
 	/**
 	 * Returns whether any non-persisted changes exist in this tree
 	 * @return boolean indicating whether any elements in this tree have been modified
+	 * @since 5.1
 	 */
 	public boolean isModified();
 
 	/**
 	 * Return whether this Settings Storage is currently read only
 	 * @return whether this storage is readonly
+	 * @since 5.1
 	 */
 	public boolean isReadOnly();
 
@@ -100,6 +104,7 @@ public interface ICSettingsStorage {
 	 * then modified flag will not be reset
 	 * @param readOnly
 	 * @param keepModify
+	 * @since 5.1
 	 */
 	void setReadOnly(boolean readOnly, boolean keepModify);
 
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICStorageElement.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICStorageElement.java
index e1a4f6e8946..f208ff1cbbc 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICStorageElement.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/ICStorageElement.java
@@ -25,7 +25,8 @@ import org.eclipse.core.runtime.CoreException;
  * @see ICSettingsStorage
  * @see ICProjectDescription
  * @see ICConfigurationDescription
- *
+ * @noextend This interface is not intended to be extended by clients.
+ * @noimplement This interface is not intended to be implemented by clients.
  */
 public interface ICStorageElement {
 
@@ -98,6 +99,7 @@ public interface ICStorageElement {
 	/**
 	 * Returns true if this storage element has child ICStorageElements
 	 * @return boolean indicating whether this ICStorageElement has children
+	 * @since 5.1
 	 */
 	boolean hasChildren();
 
@@ -152,6 +154,7 @@ public interface ICStorageElement {
 	 * getParent() of the clone should be equal to the original element.getParent().
 	 * However the clone() doesn't appear in the parent's getChildren() array.
 	 * @return ICStorageElement deep copy of this ICStorageElement
+	 * @since 5.1
 	 */
 	ICStorageElement createCopy() throws UnsupportedOperationException, CoreException;
 	
@@ -175,6 +178,7 @@ public interface ICStorageElement {
 	 * equal between the two ICStorageElements
 	 * @param other
 	 * @return boolean indicating equality
+	 * @since 5.1
 	 */
 	boolean equals(ICStorageElement other);
 }
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/XmlStorageUtil.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/XmlStorageUtil.java
index a8b04388450..54ece8c61bd 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/XmlStorageUtil.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/XmlStorageUtil.java
@@ -23,6 +23,9 @@ import org.w3c.dom.NodeList;
  * 
  * This allows importing of old style Xml trees into ICStorageElement
  * based project descriptions
+ * 
+ * @noextend This class is not intended to be subclassed by clients.
+ * @since 5.1
  */
 public class XmlStorageUtil {
 
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/util/ResourceChangeHandlerBase.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/util/ResourceChangeHandlerBase.java
index 7988ef6c4b2..cf8b79aec48 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/util/ResourceChangeHandlerBase.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/util/ResourceChangeHandlerBase.java
@@ -138,7 +138,18 @@ public abstract class ResourceChangeHandlerBase implements IResourceChangeListen
 			return false;
 		}
 	}
+
+	/**
+	 * @nooverride This method is not intended to be re-implemented or extended by clients.
+	 * @noreference This method is not intended to be referenced by clients.
+	 */
+	protected void doHahdleResourceMove(IResourceChangeEvent event, IResourceMoveHandler handler) {
+		doHandleResourceMove(event, handler);
+	}
 	
+	/**
+	 * @since 5.1
+	 */
 	protected void doHandleResourceMove(IResourceChangeEvent event, IResourceMoveHandler handler){
 		switch (event.getType()) {
 			case IResourceChangeEvent.PRE_CLOSE:
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/util/XmlStorageElement.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/util/XmlStorageElement.java
new file mode 100644
index 00000000000..845208296a7
--- /dev/null
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/core/settings/model/util/XmlStorageElement.java
@@ -0,0 +1,449 @@
+/*******************************************************************************
+ * Copyright (c) 2007, 2008 Intel Corporation and others.
+ * All rights reserved. This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License v1.0
+ * which accompanies this distribution, and is available at
+ * http://www.eclipse.org/legal/epl-v10.html
+ *
+ * Contributors:
+ *     Intel Corporation - Initial API and implementation
+ *     Anton Leherbauer (Wind River Systems) - Bug 253911
+ *******************************************************************************/
+package org.eclipse.cdt.core.settings.model.util;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import org.eclipse.cdt.core.settings.model.ICStorageElement;
+import org.eclipse.core.runtime.CoreException;
+import org.w3c.dom.Document;
+import org.w3c.dom.Element;
+import org.w3c.dom.NamedNodeMap;
+import org.w3c.dom.Node;
+import org.w3c.dom.NodeList;
+import org.w3c.dom.Text;
+
+/**
+ * @deprecated
+ * @noextend This class is not intended to be subclassed by clients.
+ * @noinstantiate This class is not intended to be instantiated by clients.
+ */
+@Deprecated
+public class XmlStorageElement implements ICStorageElement {
+
+	Element fElement;
+	private ICStorageElement fParent;
+	private List fChildList = new ArrayList();
+	private boolean fChildrenCreated;
+	private String[] fAttributeFilters;
+	private String[] fChildFilters;
+	private boolean fParentRefAlowed;
+
+	public XmlStorageElement(Element element){
+		this(element, null, false);
+	}
+
+	public XmlStorageElement(Element element, ICStorageElement parent, boolean alowReferencingParent){
+		this(element, parent, alowReferencingParent, null, null);
+	}
+
+	public XmlStorageElement(Element element,
+			ICStorageElement parent,
+			boolean alowReferencingParent,
+			String[] attributeFilters,
+			String[] childFilters){
+		fElement = element;
+		fParent = parent;
+		fParentRefAlowed = alowReferencingParent;
+		
+		if(attributeFilters != null && attributeFilters.length != 0)
+			fAttributeFilters = attributeFilters.clone();
+		
+		if(childFilters != null && childFilters.length != 0)
+			fChildFilters = childFilters.clone();
+	}
+	
+//	public String[] getAttributeFilters(){
+//		if(fAttributeFilters != null)
+//			return (String[])fAttributeFilters.clone();
+//		return null;
+//	}
+
+//	public String[] getChildFilters(){
+//		if(fChildFilters != null)
+//			return (String[])fChildFilters.clone();
+//		return null;
+//	}
+//	
+//	public boolean isParentRefAlowed(){
+//		return fParentRefAlowed;
+//	}
+
+	private void createChildren(){
+		if(fChildrenCreated)
+			return;
+		
+		fChildrenCreated = true;
+		NodeList list = fElement.getChildNodes();
+		int size = list.getLength();
+		for(int i = 0; i < size; i++){
+			Node node = list.item(i);
+			if(node.getNodeType() == Node.ELEMENT_NODE
+					&& isChildAlowed(node.getNodeName())){
+				createAddChild((Element)node, true, null, null);
+			}
+		}
+	}
+	
+	private XmlStorageElement createAddChild(Element element,
+			boolean alowReferencingParent,
+			String[] attributeFilters,
+			String[] childFilters){
+		XmlStorageElement child = createChild(element, alowReferencingParent, attributeFilters, childFilters);
+		fChildList.add(child);
+		return child; 
+	}
+	
+	protected XmlStorageElement createChild(Element element,
+			boolean alowReferencingParent,
+			String[] attributeFilters,
+			String[] childFilters){
+		return new XmlStorageElement(element, this, alowReferencingParent, attributeFilters, childFilters);
+	}
+
+	public ICStorageElement[] getChildren() {
+		return getChildren(XmlStorageElement.class);
+	}
+
+	protected ICStorageElement[] getChildren(Class clazz){
+		return getChildren(clazz, true);
+	}
+
+	protected ICStorageElement[] getChildren(boolean load){
+		return getChildren(XmlStorageElement.class, load);
+	}
+
+	protected ICStorageElement[] getChildren(Class clazz, boolean load){
+		if(load)
+			createChildren();
+
+		ICStorageElement[] children = (ICStorageElement[])java.lang.reflect.Array.newInstance(
+                                clazz, fChildList.size());
+
+		return (ICStorageElement[])fChildList.toArray(children);
+	}
+
+	public ICStorageElement getParent() {
+		return fParentRefAlowed ? fParent : null;
+	}
+
+	public String getAttribute(String name) {
+		if(isPropertyAlowed(name) && fElement.hasAttribute(name))
+			return fElement.getAttribute(name);
+		return null;
+	}
+	
+	private boolean isPropertyAlowed(String name){
+		if(fAttributeFilters != null){
+			return checkString(name, fAttributeFilters);
+		}
+		return true;
+	}
+
+	private boolean isChildAlowed(String name){
+		if(fChildFilters != null){
+			return checkString(name, fChildFilters);
+		}
+		return true;
+	}
+
+	private boolean checkString(String name, String array[]){
+		if(array.length > 0){
+			for(int i = 0; i < array.length; i++){
+				if(name.equals(array[i]))
+					return false;
+			}
+		}
+		return true;
+	}
+
+//	protected void childRemoved(ICStorageElement child) {
+//		fChildList.remove(child);
+//	}
+	
+	protected void removed(){
+//		fElement.getParentNode().removeChild(fElement);
+		fElement = null;
+//		if(fParent != null)
+//			((XmlStorageElement)fParent).childRemoved(this);
+	}
+	
+
+	public void removeChild(ICStorageElement el) {
+		if(el instanceof XmlStorageElement){
+			ICStorageElement[] children = getChildren();
+			for(int i = 0; i < children.length; i++){
+				if(children[i] == el){
+					XmlStorageElement xmlEl = (XmlStorageElement)el;
+					Node nextSibling = xmlEl.fElement.getNextSibling();
+					fElement.removeChild(xmlEl.fElement);
+					if (nextSibling != null && nextSibling.getNodeType() == Node.TEXT_NODE) {
+						String value = nextSibling.getNodeValue();
+						if (value != null && value.trim().length() == 0) {
+							// remove whitespace
+							fElement.removeChild(nextSibling);
+						}
+					}
+					fChildList.remove(el);
+					xmlEl.removed();
+				}
+			}
+		}
+		
+	}
+
+	public void removeAttribute(String name) {
+		if(isPropertyAlowed(name))
+			fElement.removeAttribute(name);
+	}
+
+	public void setAttribute(String name, String value) {
+		if(isPropertyAlowed(name))
+			fElement.setAttribute(name, value);
+	}
+	
+	public void clear(){
+		createChildren();
+
+		ICStorageElement children[] = (ICStorageElement[])fChildList.toArray(new ICStorageElement[fChildList.size()]);
+		for(int i = 0; i < children.length; i++){
+			removeChild(children[i]);
+		}
+		
+		NamedNodeMap map = fElement.getAttributes();
+		for(int i = 0; i < map.getLength(); i++){
+			Node attr = map.item(i);
+			if(isPropertyAlowed(attr.getNodeName()))
+				map.removeNamedItem(attr.getNodeName());
+		}
+		
+		NodeList list = fElement.getChildNodes();
+		for(int i = 0; i < list.getLength(); i++){
+			Node node = list.item(i);
+			if(node.getNodeType() == Node.TEXT_NODE)
+				fElement.removeChild(node);
+		}
+	}
+	
+	public ICStorageElement createChild(String name, 
+			boolean alowReferencingParent,
+			String[] attributeFilters,
+			String[] childFilters) {
+		if(!isChildAlowed(name))
+			return null;
+		Element childElement = fElement.getOwnerDocument().createElement(name);
+		fElement.appendChild(childElement);
+		return createAddChild(childElement, alowReferencingParent, attributeFilters, childFilters);
+	}
+
+	public String getName() {
+		return fElement.getNodeName();
+	}
+
+	public ICStorageElement createChild(String name) {
+		return createChild(name, true, null, null);
+	}
+
+	public String getValue() {
+		Text text = getTextChild();
+		if(text != null)
+			return text.getData();
+		return null;
+	}
+
+	public void setValue(String value) {
+		Text text = getTextChild();
+		if(value != null){
+			if(text == null){
+				text = fElement.getOwnerDocument().createTextNode(value);
+				fElement.appendChild(text);
+			} else {
+				text.setData(value);
+			}
+		} else {
+			if(text != null){
+				fElement.removeChild(text);
+			}
+		}
+	}
+	
+	private Text getTextChild(){
+		NodeList nodes = fElement.getChildNodes();
+		Text text = null;
+		for(int i = 0; i < nodes.getLength(); i++){
+			Node node = nodes.item(i);
+			if(node.getNodeType() == Node.TEXT_NODE){
+				text = (Text)node;
+				break;
+			}
+		}
+
+		return text;
+	}
+	
+	public ICStorageElement importChild(ICStorageElement el) throws UnsupportedOperationException {
+		return addChild(el, true, null, null);
+	}
+
+	public ICStorageElement addChild(ICStorageElement el, 
+			boolean alowReferencingParent,
+			String[] attributeFilters,
+			String[] childFilters) throws UnsupportedOperationException {
+		
+		if(!isChildAlowed(el.getName()))
+			return null;
+
+		if(el instanceof XmlStorageElement){
+			XmlStorageElement xmlStEl = (XmlStorageElement)el;
+			Element xmlEl = xmlStEl.fElement;
+			Document thisDoc = fElement.getOwnerDocument();
+			Document otherDoc = xmlEl.getOwnerDocument();
+			if(!thisDoc.equals(otherDoc)){
+				xmlEl = (Element)thisDoc.importNode(xmlEl, true);
+			} else {
+				xmlEl = (Element)xmlEl.cloneNode(true);
+			}
+			
+			xmlEl = (Element)fElement.appendChild(xmlEl);
+			return createAddChild(xmlEl, alowReferencingParent, attributeFilters, childFilters);
+		} else {
+			throw new UnsupportedOperationException();
+		}
+	}
+	
+	public String[] getAttributeFilters(){
+		if(fAttributeFilters != null)
+			return fAttributeFilters.clone();
+		return new String[0];
+	}
+
+	public String[] getChildFilters(){
+		if(fChildFilters != null)
+			return fChildFilters.clone();
+		return new String[0];
+	}
+
+	public boolean isParentRefAlowed(){
+		return fParentRefAlowed;
+	}
+	
+	public boolean matches(ICStorageElement el){
+		if(!getName().equals(el.getName()))
+			return false;
+		
+		if (!valuesMatch(getValue(), el.getValue()))
+			return false;
+
+		
+		String[] attrs = getAttributeNames();
+		String[] otherAttrs = el.getAttributeNames();
+		if(attrs.length != otherAttrs.length)
+			return false;
+		
+		if(attrs.length != 0){
+			Set set = new HashSet(Arrays.asList(attrs));
+			set.removeAll(Arrays.asList(otherAttrs));
+			if(set.size() != 0)
+				return false;
+
+			for(int i = 0; i < attrs.length; i++){
+				if(!getAttribute(attrs[i]).equals(el.getAttribute(attrs[i])))
+					return false;
+			}
+
+		}
+		
+		
+		XmlStorageElement[] children = (XmlStorageElement[])getChildren();
+		ICStorageElement[] otherChildren = el.getChildren();
+		
+		if(children.length != otherChildren.length)
+			return false;
+		
+		if(children.length != 0){
+			for(int i = 0; i < children.length; i++){
+				if(!children[i].matches(otherChildren[i]))
+					return false;
+			}
+		}
+		
+		return true;
+	}
+
+	private static boolean valuesMatch(String value, String other) {
+		if(value == null) {
+			return other == null || other.trim().length() == 0;
+		} else if (other == null) {
+			return value.trim().length() == 0;
+		} else {
+			return value.trim().equals(other.trim());
+		}
+	}
+
+	public String[] getAttributeNames() {
+		NamedNodeMap nodeMap = fElement.getAttributes();
+		int length = nodeMap.getLength();
+		List list = new ArrayList(length);
+		for(int i = 0; i < length; i++){
+			Node node = nodeMap.item(i);
+			String name = node.getNodeName();
+			if(isPropertyAlowed(name))
+				list.add(name);
+		}
+		return (String[])list.toArray(new String[list.size()]);
+	}
+
+	/**
+	 * @since 5.1
+	 */
+	public ICStorageElement createCopy() throws UnsupportedOperationException, CoreException {
+		// todo Auto-generated method stub
+		return null;
+	}
+
+	/**
+	 * @since 5.1
+	 */
+	public boolean equals(ICStorageElement other) {
+		// todo Auto-generated method stub
+		return false;
+	}
+
+	/**
+	 * @since 5.1
+	 */
+	public ICStorageElement[] getChildrenByName(String name) {
+		// todo Auto-generated method stub
+		return null;
+	}
+
+	/**
+	 * @since 5.1
+	 */
+	public boolean hasAttribute(String name) {
+		// todo Auto-generated method stub
+		return false;
+	}
+
+	/**
+	 * @since 5.1
+	 */
+	public boolean hasChildren() {
+		// todo Auto-generated method stub
+		return false;
+	}
+
+}
diff --git a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/SynchronizedStorageElement.java b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/SynchronizedStorageElement.java
index 045a1e86335..b302db87460 100644
--- a/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/SynchronizedStorageElement.java
+++ b/core/org.eclipse.cdt.core/model/org/eclipse/cdt/internal/core/settings/model/SynchronizedStorageElement.java
@@ -65,6 +65,26 @@ public class SynchronizedStorageElement implements ICStorageElement {
 		return new SynchronizedStorageElement(el);
 	}
 
+	/**
+	 * Create a synchronized storage element from an existing storage element
+	 * All access to this ICStorageElement tree will be synchronized on the
+	 * returned ICStorageElement object.
+	 * @param el
+	 * @param lock
+	 * @return SynchronizedStorageElement wrapping the original ICStorageElement
+	 */
+	public static SynchronizedStorageElement synchronizedElement(ICStorageElement el, Object lock) {
+		return new SynchronizedStorageElement(el, lock);
+	}
+	
+	/**
+	 * @return the lock used to synchronize this SynchronizedStorage and its children
+	 */
+	public Object lock() {
+		return fLock;
+	}
+
+
 	public void clear() {
 		synchronized (fLock) {
 			fEl.clear();
diff --git a/core/org.eclipse.cdt.core/schema/CProjectDescriptionStorage.exsd b/core/org.eclipse.cdt.core/schema/CProjectDescriptionStorage.exsd
index 5ea7a2549e0..fbf9952a7c8 100644
--- a/core/org.eclipse.cdt.core/schema/CProjectDescriptionStorage.exsd
+++ b/core/org.eclipse.cdt.core/schema/CProjectDescriptionStorage.exsd
@@ -13,7 +13,7 @@
    <element name="extension">
       <annotation>
          <appinfo>
-            <meta.element />
+            <meta.element internal="true" />
          </appinfo>
       </annotation>
       <complexType>
diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICDescriptor.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICDescriptor.java
index 9576a4f0f9b..a7401e723a2 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICDescriptor.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/core/ICDescriptor.java
@@ -17,7 +17,7 @@ import org.eclipse.cdt.core.settings.model.ICProjectDescription;
 import org.eclipse.cdt.core.settings.model.ICStorageElement;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.runtime.CoreException;
-
+import org.w3c.dom.Element;
 /**
  * Models meta-data stored with a CDT project
  *
@@ -27,6 +27,9 @@ import org.eclipse.core.runtime.CoreException;
  *
  * @see ICDescriptorOperation
  * @see ICDescriptorManager
+ * 
+ * @noextend This interface is not intended to be extended by clients.
+ * @noimplement This interface is not intended to be implemented by clients.
  */
 public interface ICDescriptor {
 	public ICOwnerInfo getProjectOwner();
@@ -110,12 +113,26 @@ public interface ICDescriptor {
 	 */
 	public ICStorageElement getProjectStorageElement(String id) throws CoreException;
 
+	/**
+	 * This method has been superceded by {@link ICDescriptor#getProjectStorageElement(String)}
+	 * @param id an identifier that uniquely identifies the client
+	 * @return a non-null {@link Element} to which client specific meta-data may be attached
+	 * @throws CoreException
+	 * @deprecated
+	 * @noreference This method is not intended to be referenced by clients.
+	 * @use {@link ICDescriptor#getProjectStorageElement(String)}
+	 */
+	@Deprecated
+	public Element getProjectData(String id) throws CoreException;
+
 	/**
 	 * Remove the storage element with the given ID from the tree
 	 * @param id
+	 * @return the ICStorageElement removed or null if there was none for id
 	 * @throws CoreException
+	 * @since 5.1
 	 */
-	public void removeProjectStorageElement(String id) throws CoreException;
+	public ICStorageElement removeProjectStorageElement(String id) throws CoreException;
 
 	/**
 	 * Saves any changes made to {@link ICStorageElement} objects obtained from {@link #getProjectStorageElement(String)}
@@ -130,4 +147,5 @@ public interface ICDescriptor {
 	 * @return the current setting {@link ICConfigurationDescription}
 	 */
 	ICConfigurationDescription getConfigurationDescription();
+
 }
diff --git a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CConfigBasedDescriptor.java b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CConfigBasedDescriptor.java
index c19e5f8d5a4..3baa875ec32 100644
--- a/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CConfigBasedDescriptor.java
+++ b/core/org.eclipse.cdt.core/src/org/eclipse/cdt/internal/core/CConfigBasedDescriptor.java
@@ -12,6 +12,9 @@
  *******************************************************************************/
 package org.eclipse.cdt.internal.core;
 
+import java.lang.reflect.InvocationHandler;
+import java.lang.reflect.Method;
+import java.lang.reflect.Proxy;
 import java.text.MessageFormat;
 import java.util.HashMap;
 import java.util.LinkedHashSet;
@@ -36,6 +39,8 @@ import org.eclipse.cdt.internal.core.settings.model.CProjectDescriptionManager;
 import org.eclipse.cdt.internal.core.settings.model.ExceptionFactory;
 import org.eclipse.cdt.internal.core.settings.model.IInternalCCfgInfo;
 import org.eclipse.cdt.internal.core.settings.model.SynchronizedStorageElement;
+import org.eclipse.cdt.internal.core.settings.model.xml.XmlStorage;
+import org.eclipse.cdt.internal.core.settings.model.xml.XmlStorageElement;
 import org.eclipse.core.resources.IProject;
 import org.eclipse.core.resources.ResourcesPlugin;
 import org.eclipse.core.runtime.CoreException;
@@ -46,6 +51,8 @@ import org.eclipse.core.runtime.NullProgressMonitor;
 import org.eclipse.core.runtime.Status;
 import org.eclipse.core.runtime.jobs.ILock;
 import org.eclipse.core.runtime.jobs.Job;
+import org.w3c.dom.Element;
+import org.w3c.dom.Node;
 
 /**
  * Concrete ICDescriptor for a Project.
@@ -440,10 +447,88 @@ final public class CConfigBasedDescriptor implements ICDescriptor {
 		}
 	}
 
-	public void removeProjectStorageElement(String id) throws CoreException {
+	/**
+	 * Backwards compatibility method which provides an XML Element.
+	 * Currently relies on the fact that the only implementation if ICStorageElement
+	 * in the core is XmlStorageElement.
+	 */
+	public Element getProjectData(String id) throws CoreException {
 		try {
 			fLock.acquire();
-			fStorageDataElMap.put(id, null);
+			// Check if the storage element already exists in our local map
+			SynchronizedStorageElement storageEl = fStorageDataElMap.get(id);
+			ICStorageElement el;
+			if(storageEl == null) {
+				el = fCfgDes.getStorage(id, true);
+				try {
+					el = el.createCopy();
+				} catch (UnsupportedOperationException e) {
+					throw ExceptionFactory.createCoreException(e);
+				}
+
+				if (!(el instanceof XmlStorageElement))
+					throw ExceptionFactory.createCoreException(
+							"Internal Error: getProjectData(...) currently only supports XmlStorageElement types.", new Exception()); //$NON-NLS-1$
+
+				// Get the underlying Xml Element
+				final Element xmlEl = ((XmlStorageElement)el).fElement;
+				// This proxy synchronizes the storage element's root XML Element
+				el = new XmlStorageElement((Element)Proxy.newProxyInstance(Element.class.getClassLoader(), new Class[]{Element.class}, new InvocationHandler(){
+					public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+						Method realMethod = xmlEl.getClass().getMethod(method.getName(), method.getParameterTypes());
+						// Now just execute the method
+						synchronized (xmlEl) {
+							// If requesting the parent node, then we need another proxy
+							// so that parent.removeChildNode(...) 'does the right thing'
+							if (method.getName().equals("getParentNode")) { //$NON-NLS-1$
+								final Node parent = (Node)realMethod.invoke(xmlEl, args);
+								Node parentProxy = (Node)Proxy.newProxyInstance(Node.class.getClassLoader(), new Class[]{Node.class}, new InvocationHandler(){
+									public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
+										Method realMethod = parent.getClass().getMethod(method.getName(), method.getParameterTypes());
+										synchronized (xmlEl) {
+											// Handle the remove child case
+											if (method.getName().equals("removeChild")) { //$NON-NLS-1$
+												if (args[0] instanceof Element && ((Element)args[0]).getAttribute(
+														XmlStorage.MODULE_ID_ATTRIBUTE).length() > 0) {
+													ICStorageElement removed = removeProjectStorageElement(((Element)args[0]).getAttribute(
+															XmlStorage.MODULE_ID_ATTRIBUTE));
+													if (removed != null)
+														return ((XmlStorageElement)((SynchronizedStorageElement)removed).getOriginalElement()).fElement;
+													return null;
+												}
+											}
+											// else return the realMethod
+											return realMethod.invoke(parent, args);
+										}
+									}
+								});
+								return parentProxy;
+							}
+							// Otherwise just execute the method
+							return realMethod.invoke(xmlEl, args);
+						}
+					}
+				}));
+
+				storageEl = SynchronizedStorageElement.synchronizedElement(el, xmlEl);
+				fStorageDataElMap.put(id, storageEl);
+			} else {
+				el = storageEl.getOriginalElement();
+				if (!(el instanceof XmlStorageElement))
+					throw ExceptionFactory.createCoreException(
+							"Internal Error: getProjectData(...) currently only supports XmlStorageElement types.", new Exception()); //$NON-NLS-1$
+			}
+
+			return ((XmlStorageElement)el).fElement;
+		} finally {
+			fLock.release();
+		}
+	}
+
+	public ICStorageElement removeProjectStorageElement(String id) throws CoreException {
+		try {
+			fLock.acquire();
+			return fStorageDataElMap.put(id, null);
 		} finally {
 			fLock.release();
 		}
@@ -623,7 +708,7 @@ final public class CConfigBasedDescriptor implements ICDescriptor {
 
 					if (synchStor != null ) {
 						// Lock the synchronized storage element to prevent further changes
-						synchronized (synchStor) {
+						synchronized (synchStor.lock()) {
 							if(reconcile(id, synchStor.getOriginalElement(), des))
 								reconciled = true;
 						}