diff -r f4a875afac55 projectui/src/org/netbeans/modules/project/ui/OpenProjectList.java
--- a/projectui/src/org/netbeans/modules/project/ui/OpenProjectList.java	Wed Dec 03 10:10:50 2008 +0100
+++ b/projectui/src/org/netbeans/modules/project/ui/OpenProjectList.java	Wed Dec 03 10:05:49 2008 +0100
@@ -91,6 +91,7 @@
 import org.netbeans.modules.project.uiapi.ProjectOpenedTrampoline;
 import org.netbeans.spi.project.SubprojectProvider;
 import org.netbeans.spi.project.ui.PrivilegedTemplates;
+import org.netbeans.spi.project.ui.ProjectInitializationHook;
 import org.netbeans.spi.project.ui.ProjectOpenedHook;
 import org.netbeans.spi.project.ui.RecommendedTemplates;
 import org.openide.ErrorManager;
@@ -220,6 +221,30 @@
             }
         }
         return wrap;
+    }
+
+    private static Project doInitializeProject(Project p) {
+        ClassLoader l = ProjectOpenedHook.class.getClassLoader();
+        try {
+            Class.forName(ProjectOpenedHook.class.getName(), true, l);
+        } catch (ClassNotFoundException ex) {
+            Exceptions.printStackTrace(ex);
+        }
+        INIT: for (;;) {
+            Collection<? extends ProjectInitializationHook> initHooks = p.getLookup().lookupAll(ProjectInitializationHook.class);
+            assert initHooks.size() <= 1 : "There can be at most one hook " + initHooks;
+            for (ProjectInitializationHook h : initHooks) {
+                Project np = ProjectOpenedTrampoline.DEFAULT.projectWillBeOpened(h);
+                if (np == null) {
+                    return np;
+                }
+                if (np != p) {
+                    p = np;
+                    continue INIT;
+                }
+            }
+            return p;
+        }
     }
 
     /** Modifications to the recentTemplates variables shall be done only 
@@ -352,6 +377,12 @@
                     }
                     p = toOpenProjects.remove();
                     LOGGER.log(Level.FINER, "after remove {0}", toOpenProjects); // NOI18N
+                }
+                LOGGER.log(Level.FINE, "about to init a project {0}", p); // NOI18N
+                p = doInitializeProject(p);
+                if (p == null) {
+                    LOGGER.log(Level.FINE, "project shall not be opened"); // NOI18N
+                    continue;
                 }
                 LOGGER.log(Level.FINE, "about to open a project {0}", p); // NOI18N
                 if (notifyOpened(p)) {
@@ -1031,9 +1062,14 @@
         }
     }
     
-    private boolean doOpenProject(final Project p) {
+    private boolean doOpenProject(Project p) {
         boolean recentProjectsChanged;
         LOGGER.finer("doOpenProject(): opening project " + p.toString());
+        p = doInitializeProject(p);
+        if (p == null) {
+            return false;
+        }
+
         synchronized (this) {
             if (openProjects.contains(p)) {
                 return false;
@@ -1049,12 +1085,12 @@
         logProjects("doOpenProject(): openProjects == ", openProjects.toArray(new Project[0])); // NOI18N
         // Notify projects opened
         notifyOpened(p);
-        
+
+        final Project openFilesFor = p;
         Mutex.EVENT.readAccess(new Action<Void>() {
             public Void run() {
                 // Open project files
-                ProjectUtilities.openProjectFiles(p);
-                
+                ProjectUtilities.openProjectFiles(openFilesFor);
                 return null;
             }
         });
diff -r f4a875afac55 projectui/test/unit/src/org/netbeans/modules/project/ui/OpenProjectInitializeTest.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/projectui/test/unit/src/org/netbeans/modules/project/ui/OpenProjectInitializeTest.java	Wed Dec 03 10:05:50 2008 +0100
@@ -0,0 +1,274 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
+ *
+ * The contents of this file are subject to the terms of either the GNU
+ * General Public License Version 2 only ("GPL") or the Common
+ * Development and Distribution License("CDDL") (collectively, the
+ * "License"). You may not use this file except in compliance with the
+ * License. You can obtain a copy of the License at
+ * http://www.netbeans.org/cddl-gplv2.html
+ * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
+ * specific language governing permissions and limitations under the
+ * License.  When distributing the software, include this License Header
+ * Notice in each file and include the License file at
+ * nbbuild/licenses/CDDL-GPL-2-CP.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the GPL Version 2 section of the License file that
+ * accompanied this code. If applicable, add the following below the
+ * License Header, with the fields enclosed by brackets [] replaced by
+ * your own identifying information:
+ * "Portions Copyrighted [year] [name of copyright owner]"
+ *
+ * Contributor(s):
+ *
+ * The Original Software is NetBeans. The Initial Developer of the Original
+ * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
+ * Microsystems, Inc. All Rights Reserved.
+ *
+ * If you wish your version of this file to be governed by only the CDDL
+ * or only the GPL Version 2, indicate your decision by adding
+ * "[Contributor] elects to include this software in this distribution
+ * under the [CDDL or GPL Version 2] license." If you do not indicate a
+ * single choice of license, a recipient has the option to distribute
+ * your version of this file under either the CDDL, the GPL Version 2 or
+ * to extend the choice of license to its licensees as provided above.
+ * However, if you add GPL Version 2 code and therefore, elected the GPL
+ * Version 2 license, then the option applies only if the new code is
+ * made subject to such option by the copyright holder.
+ */
+
+package org.netbeans.modules.project.ui;
+
+import java.io.IOException;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.TimeoutException;
+import java.util.logging.Level;
+import org.netbeans.api.project.Project;
+import org.netbeans.api.project.ProjectManager;
+import org.netbeans.api.project.ui.OpenProjects;
+import org.netbeans.junit.MockServices;
+import org.netbeans.junit.NbTestCase;
+import org.netbeans.spi.project.ProjectFactory;
+import org.netbeans.spi.project.ProjectState;
+import org.netbeans.spi.project.ui.ProjectInitializationHook;
+import org.netbeans.spi.project.ui.ProjectOpenedHook;
+import org.openide.filesystems.FileObject;
+import org.openide.filesystems.FileUtil;
+import org.openide.util.Exceptions;
+import org.openide.util.Lookup;
+import org.openide.util.RequestProcessor;
+import org.openide.util.lookup.AbstractLookup;
+import org.openide.util.lookup.InstanceContent;
+
+/** Verify ProjectInitializationHook is called.
+ *
+ * @author Jaroslav Tulach
+ */
+public class OpenProjectInitializeTest extends NbTestCase {
+    FileObject f1_1_open, f1_2_open, f1_3_close;
+    FileObject f2_1_open;
+
+    Project project1;
+
+    public OpenProjectInitializeTest (String testName) {
+        super (testName);
+    }
+
+    @Override
+    protected Level logLevel() {
+        return Level.FINE;
+    }
+
+    @Override
+    protected void setUp () throws Exception {
+        super.setUp ();
+        MockServices.setServices(MyFactory.class);
+        clearWorkDir ();
+        
+        FileObject workDir = FileUtil.toFileObject (getWorkDir ());
+    
+        FileObject p1 = workDir.createFolder("prjDir");
+        f1_1_open = p1.createData("f1_1.java");
+        f1_2_open = p1.createData("f1_2.java");
+        f1_3_close = p1.createData("f1_3.java");
+
+        MyFactory.toRet = new MyProject(p1);
+        project1 = ProjectManager.getDefault ().findProject (p1);
+        assertNotNull("Project found", project1);
+
+        assertEquals("No open prjs", 0, OpenProjects.getDefault().openProjects().get().length);
+    }
+    
+    @Override
+    protected void tearDown () throws Exception {
+        OpenProjectList.getDefault().close(OpenProjectList.getDefault().getOpenProjects(), false);
+        assertEquals("No open prjs", 0, OpenProjects.getDefault().openProjects().get().length);
+    }
+
+    public void testOpenWithOneRedirect() throws Exception {
+        assertTrue ("No project is open.", OpenProjectList.getDefault ().getOpenProjects ().length == 0);
+
+        MyProject project2 = new MyProject(project1.getProjectDirectory());
+
+        InitHook h = new InitHook(project2);
+        MyProject tp = (MyProject)project1;
+        h.stateToClose = tp.state;
+        tp.ic.add(h);
+
+        OpenProjectList.getDefault ().open(tp, true);
+
+        Project[] open = OpenProjectList.getDefault().getOpenProjects();
+        assertEquals("One is open", 1, open.length);
+        assertEquals("Redirect gets opened", project2, open[0]);
+        assertEquals("Its open hook is called", 1, project2.openHook.opened);
+        assertEquals("Open hook of project1 ignored", 0, tp.openHook.opened);
+    }
+
+    public void testOpenWithTwoRedirect() throws Exception {
+        assertTrue ("No project is open.", OpenProjectList.getDefault ().getOpenProjects ().length == 0);
+
+        MyProject project2 = new MyProject(project1.getProjectDirectory());
+        MyProject project3 = new MyProject(project1.getProjectDirectory());
+
+        InitHook h = new InitHook(project2);
+        InitHook h2 = new InitHook(project3);
+        MyProject tp = (MyProject)project1;
+        h2.stateToClose = tp.state;
+        tp.ic.add(h2);
+        project2.ic.add(h2);
+
+        OpenProjectList.getDefault ().open (tp, true);
+
+        Project[] open = OpenProjectList.getDefault().getOpenProjects();
+        assertEquals("One is open", 1, open.length);
+        assertEquals("Project3 gets opened", project3, open[0]);
+        assertEquals("Project3 open hook is called", 1, project3.openHook.opened);
+        assertEquals("Project2 open hook is ignored", 0, project2.openHook.opened);
+        assertEquals("Open hook of project1 ignored", 0, tp.openHook.opened);
+    }
+
+    public void testNullOpensNoProject() throws Exception {
+        assertTrue ("No project is open.", OpenProjectList.getDefault ().getOpenProjects ().length == 0);
+
+        InitHook h = new InitHook(null);
+        MyProject tp = (MyProject)project1;
+        tp.ic.add(h);
+
+        OpenProjectList.getDefault ().open (tp, true);
+
+        Project[] open = OpenProjectList.getDefault().getOpenProjects();
+        assertEquals("Nothing is open", 0, open.length);
+        assertEquals("Open hook of project1 ignored", 0, tp.openHook.opened);
+    }
+
+    public static class MyFactory implements ProjectFactory {
+        static MyProject toRet;
+
+        public boolean isProject(FileObject d) {
+            return toRet != null && toRet.getProjectDirectory().equals(d);
+        }
+
+        public Project loadProject(FileObject projectDirectory, ProjectState state) throws IOException {
+            if (toRet != null && projectDirectory.equals(toRet.getProjectDirectory())) {
+                MyProject h = toRet;
+                h.state = state;
+                toRet = null;
+                return h;
+            }
+            return null;
+        }
+
+        public void saveProject(Project project) throws IOException, ClassCastException {
+        }
+    } // end of MyFactory
+
+
+
+    private static class MyProject implements Project {
+        final FileObject fo;
+        final Lookup lookup;
+        final InstanceContent ic;
+        final OpenHook openHook;
+        ProjectState state;
+
+        public MyProject(FileObject fo) {
+            this.fo = fo;
+            this.ic = new InstanceContent();
+            this.lookup = new AbstractLookup(ic);
+            this.openHook = new OpenHook();
+            ic.add(openHook);
+        }
+
+        public FileObject getProjectDirectory() {
+            return fo;
+        }
+
+        public Lookup getLookup() {
+            return lookup;
+        }
+    } // end of MyProject
+    private static class InitHook extends ProjectInitializationHook {
+        MyProject willBeOpened;
+        ProjectState stateToClose;
+        public InitHook(MyProject next) {
+            willBeOpened = next;
+        }
+
+        @Override
+        protected Project projectWillBeOpened() {
+            if (stateToClose != null) {
+                stateToClose.notifyDeleted();
+                stateToClose = null;
+            }
+            if (willBeOpened == null) {
+                return null;
+            }
+            try {
+                MyFactory.toRet = willBeOpened;
+                Project found = ProjectManager.getDefault().findProject(willBeOpened.getProjectDirectory());
+                assertEquals("The right one found", willBeOpened, found);
+                return found;
+            } catch (IOException ex) {
+                Exceptions.printStackTrace(ex);
+            } catch (IllegalArgumentException ex) {
+                Exceptions.printStackTrace(ex);
+            }
+            return null;
+        }
+    } // end of InitHook
+    private static class OpenHook extends ProjectOpenedHook
+    implements Runnable {
+        int opened = 0;
+        int closed = 0;
+        
+        private Object result;
+        
+        protected void projectClosed() {
+            closed++;
+            assertFalse("Working on", OpenProjects.getDefault().openProjects().isDone());
+            RequestProcessor.getDefault().post(this).waitFinished();
+            assertNotNull("some result computed", result);
+            assertEquals("It is time out exception", TimeoutException.class, result.getClass());
+        }
+        
+        protected void projectOpened() {
+            opened++;
+            assertFalse("Working on", OpenProjects.getDefault().openProjects().isDone());
+            RequestProcessor.getDefault().post(this).waitFinished();
+            assertNotNull("some result computed", result);
+            assertEquals("It is time out exception", TimeoutException.class, result.getClass());
+        }
+        
+        public void run() {
+            try {
+                result = OpenProjects.getDefault().openProjects().get(100, TimeUnit.MILLISECONDS);
+            } catch (Exception ex) {
+                result = ex;
+    }
+        }
+    }
+
+    
+}
diff -r f4a875afac55 projectuiapi/apichanges.xml
--- a/projectuiapi/apichanges.xml	Wed Dec 03 10:10:50 2008 +0100
+++ b/projectuiapi/apichanges.xml	Wed Dec 03 10:05:50 2008 +0100
@@ -104,6 +104,23 @@
     <!-- ACTUAL CHANGES BEGIN HERE: -->
 
     <changes>
+        <change id="ProjectInitializationHook">
+            <api name="general"/>
+            <summary>Add ProjectInitializationHook</summary>
+            <version major="1" minor="34"/>
+            <date day="20" month="12" year="2008"/>
+            <author login="jtulach"/>
+            <compatibility addition="yes" binary="compatible" deletion="no" deprecation="no" modification="no" semantic="compatible" source="compatible"/>
+            <description>
+                <p>
+                <code>ProjectInitializationHook</code> can be provided by Project's
+                to be notified that the project is about to become opened and
+                prevent that by finding proper substitute.
+                </p>
+            </description>
+            <class package="org.netbeans.spi.project.ui" name="ProjectInitializationHook"/>
+            <issue number="154427"/>
+        </change>
         <change id="nodefactory-ann">
             <api name="general"/>
             <summary>Add annotation @NodeFactory.Registration</summary>
diff -r f4a875afac55 projectuiapi/nbproject/project.properties
--- a/projectuiapi/nbproject/project.properties	Wed Dec 03 10:10:50 2008 +0100
+++ b/projectuiapi/nbproject/project.properties	Wed Dec 03 10:05:50 2008 +0100
@@ -39,7 +39,7 @@
 
 javac.compilerargs=-Xlint -Xlint:-serial
 javac.source=1.5
-spec.version.base=1.33.0
+spec.version.base=1.34.0
 is.autoload=true
 javadoc.arch=${basedir}/arch.xml
 javadoc.apichanges=${basedir}/apichanges.xml
diff -r f4a875afac55 projectuiapi/src/org/netbeans/modules/project/uiapi/ProjectOpenedTrampoline.java
--- a/projectuiapi/src/org/netbeans/modules/project/uiapi/ProjectOpenedTrampoline.java	Wed Dec 03 10:10:50 2008 +0100
+++ b/projectuiapi/src/org/netbeans/modules/project/uiapi/ProjectOpenedTrampoline.java	Wed Dec 03 10:05:50 2008 +0100
@@ -41,6 +41,8 @@
 
 package org.netbeans.modules.project.uiapi;
 
+import org.netbeans.api.project.Project;
+import org.netbeans.spi.project.ui.ProjectInitializationHook;
 import org.netbeans.spi.project.ui.ProjectOpenedHook;
 
 /**
@@ -62,6 +64,9 @@
     
     /** Used by {@link ProjectOpenedHook}. */
     protected ProjectOpenedTrampoline() {}
+
+    /** Delegates to {@link ProjectInitializationHook#projectWillBeOpened()}. */
+    public abstract Project projectWillBeOpened(ProjectInitializationHook hook);
     
     /** Delegates to {@link ProjectOpenedHook#projectOpened}. */
     public abstract void projectOpened(ProjectOpenedHook hook);
diff -r f4a875afac55 projectuiapi/src/org/netbeans/spi/project/ui/ProjectInitializationHook.java
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/projectuiapi/src/org/netbeans/spi/project/ui/ProjectInitializationHook.java	Wed Dec 03 10:05:50 2008 +0100
@@ -0,0 +1,76 @@
+/*
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
+ *
+ * Copyright 1997-2007 Sun Microsystems, Inc. All rights reserved.
+ *
+ * The contents of this file are subject to the terms of either the GNU
+ * General Public License Version 2 only ("GPL") or the Common
+ * Development and Distribution License("CDDL") (collectively, the
+ * "License"). You may not use this file except in compliance with the
+ * License. You can obtain a copy of the License at
+ * http://www.netbeans.org/cddl-gplv2.html
+ * or nbbuild/licenses/CDDL-GPL-2-CP. See the License for the
+ * specific language governing permissions and limitations under the
+ * License.  When distributing the software, include this License Header
+ * Notice in each file and include the License file at
+ * nbbuild/licenses/CDDL-GPL-2-CP.  Sun designates this
+ * particular file as subject to the "Classpath" exception as provided
+ * by Sun in the GPL Version 2 section of the License file that
+ * accompanied this code. If applicable, add the following below the
+ * License Header, with the fields enclosed by brackets [] replaced by
+ * your own identifying information:
+ * "Portions Copyrighted [year] [name of copyright owner]"
+ *
+ * Contributor(s):
+ *
+ * The Original Software is NetBeans. The Initial Developer of the Original
+ * Software is Sun Microsystems, Inc. Portions Copyright 1997-2006 Sun
+ * Microsystems, Inc. All Rights Reserved.
+ *
+ * If you wish your version of this file to be governed by only the CDDL
+ * or only the GPL Version 2, indicate your decision by adding
+ * "[Contributor] elects to include this software in this distribution
+ * under the [CDDL or GPL Version 2] license." If you do not indicate a
+ * single choice of license, a recipient has the option to distribute
+ * your version of this file under either the CDDL, the GPL Version 2 or
+ * to extend the choice of license to its licensees as provided above.
+ * However, if you add GPL Version 2 code and therefore, elected the GPL
+ * Version 2 license, then the option applies only if the new code is
+ * made subject to such option by the copyright holder.
+ */
+
+package org.netbeans.spi.project.ui;
+
+import org.netbeans.api.project.Project;
+
+/**
+ * A hook which can be run when a project is about to be "opened" the GUI.
+ * Called before {@link ProjectOpenedHook}'s <code>projectOpened</code> method
+ * is called. Register an instance of this class into {@link Project#getLookup()}
+ * method to perform pre-initialization actions, including finding another 
+ * project to represent this directory.
+ * </p>
+ * @see ProjectOpenedHook#projectOpened
+ * @see org.netbeans.api.project.Project#getLookup
+ * 
+ * @author Jaroslav Tulach
+ * @since 1.34
+ */
+public abstract class ProjectInitializationHook {
+    /**
+     * Default constructor for use by subclasses.
+     */
+    protected ProjectInitializationHook() {}
+    
+    /**
+     * Called when a project is about to be open in the GUI. The project has
+     * a chance to initialize necessary system resources and potentially
+     * also provide a delegate that shall be open instead of the project
+     * itself.
+     *
+     * @return either project that shall be installed instead of the one
+     *   providing this hook, the project itself, or
+     *   <code>null</code> which means that no project will be opened at all
+     */
+    protected abstract Project projectWillBeOpened();
+}
diff -r f4a875afac55 projectuiapi/src/org/netbeans/spi/project/ui/ProjectOpenedHook.java
--- a/projectuiapi/src/org/netbeans/spi/project/ui/ProjectOpenedHook.java	Wed Dec 03 10:10:50 2008 +0100
+++ b/projectuiapi/src/org/netbeans/spi/project/ui/ProjectOpenedHook.java	Wed Dec 03 10:05:50 2008 +0100
@@ -41,6 +41,7 @@
 
 package org.netbeans.spi.project.ui;
 
+import org.netbeans.api.project.Project;
 import org.netbeans.modules.project.uiapi.ProjectOpenedTrampoline;
 
 /**
@@ -82,6 +83,11 @@
             }
             public void projectClosed(ProjectOpenedHook hook) {
                 hook.projectClosed();
+            }
+
+            @Override
+            public Project projectWillBeOpened(ProjectInitializationHook hook) {
+                return hook.projectWillBeOpened();
             }
         };
     }