Index: projectui/src/org/netbeans/modules/project/ui/OpenProjectList.java
===================================================================
RCS file: /cvs/projects/projectui/src/org/netbeans/modules/project/ui/OpenProjectList.java,v
retrieving revision 1.35
diff -u -r1.35 OpenProjectList.java
--- projectui/src/org/netbeans/modules/project/ui/OpenProjectList.java	20 Jul 2005 21:12:05 -0000	1.35
+++ projectui/src/org/netbeans/modules/project/ui/OpenProjectList.java	25 Aug 2005 09:01:02 -0000
@@ -254,6 +254,10 @@
     
     public void setMainProject( Project mainProject ) {
         synchronized ( this ) {
+            if (!openProjects.contains(mainProject)) {
+                throw new IllegalArgumentException("Project " + ProjectUtils.getInformation(mainProject).getDisplayName() + " is not open and cannot be set as main.");
+            }
+        
             this.mainProject = mainProject;
             saveMainProject( mainProject );
         }
Index: projectui/src/org/netbeans/modules/project/ui/OpenProjectsTrampolineImpl.java
===================================================================
RCS file: /cvs/projects/projectui/src/org/netbeans/modules/project/ui/OpenProjectsTrampolineImpl.java,v
retrieving revision 1.4
diff -u -r1.4 OpenProjectsTrampolineImpl.java
--- projectui/src/org/netbeans/modules/project/ui/OpenProjectsTrampolineImpl.java	15 Dec 2004 10:36:28 -0000	1.4
+++ projectui/src/org/netbeans/modules/project/ui/OpenProjectsTrampolineImpl.java	25 Aug 2005 09:01:02 -0000
@@ -62,4 +62,12 @@
         }
     }
         
+    public Project getMainProject() {
+        return OpenProjectList.getDefault().getMainProject();
+    }
+    
+    public void setMainProject(Project project) {
+        OpenProjectList.getDefault().setMainProject(project);
+    }
+    
 }
Index: projectui/test/unit/src/org/netbeans/modules/project/ui/OpenProjectListTest.java
===================================================================
RCS file: /cvs/projects/projectui/test/unit/src/org/netbeans/modules/project/ui/OpenProjectListTest.java,v
retrieving revision 1.5
diff -u -r1.5 OpenProjectListTest.java
--- projectui/test/unit/src/org/netbeans/modules/project/ui/OpenProjectListTest.java	11 Jul 2005 12:18:11 -0000	1.5
+++ projectui/test/unit/src/org/netbeans/modules/project/ui/OpenProjectListTest.java	25 Aug 2005 09:01:02 -0000
@@ -213,6 +213,69 @@
         assertFalse("project2 is not in recent projects list", OpenProjectList.getDefault().getRecentProjects().contains(project2));
     }
     
+    public void testMainProject() throws Exception {
+        FileObject workDir = FileUtil.toFileObject (getWorkDir ());
+        
+        FileObject p1 = workDir.createFolder("p1");
+        FileObject p1TestProject = p1.createFolder("testproject");
+        
+        Project project1 = ProjectManager.getDefault().findProject(p1);
+        
+        assertNotNull("project1 is recognized", project1);
+        
+        FileObject p2 = workDir.createFolder("p2");
+        FileObject p2TestProject = p2.createFolder("testproject");
+        
+        Project project2 = ProjectManager.getDefault().findProject(p2);
+        
+        assertNotNull("project2 is recognized", project2);
+        
+        FileObject p3 = workDir.createFolder("p3");
+        FileObject p3TestProject = p3.createFolder("testproject");
+        
+        Project project3 = ProjectManager.getDefault().findProject(p3);
+        
+        assertNotNull("project3 is recognized", project3);
+        
+        assertNull("no main project set when OPL is empty", OpenProjectList.getDefault().getMainProject());
+        
+        OpenProjectList.getDefault().open(project1);
+        
+        assertNull("open project does not change main project", OpenProjectList.getDefault().getMainProject());
+        
+        OpenProjectList.getDefault().setMainProject(project1);
+        
+        assertTrue("main project correctly set", OpenProjectList.getDefault().getMainProject() == project1);
+        
+        OpenProjectList.getDefault().open(project2);
+        
+        assertTrue("open project does not change main project", OpenProjectList.getDefault().getMainProject() == project1);
+        
+        OpenProjectList.getDefault().close(new Project[] {project1});
+        
+        assertNull("no main project set when main project is closed", OpenProjectList.getDefault().getMainProject());
+        
+        boolean exceptionThrown = false;
+        
+        try {
+            OpenProjectList.getDefault().setMainProject(project3);
+        } catch (IllegalArgumentException e) {
+            exceptionThrown = true;
+        }
+        
+        assertTrue("IAE thrown when trying to set main project that is not opened", exceptionThrown);
+        
+        //the same for a previously opened project:
+        exceptionThrown = false;
+        
+        try {
+            OpenProjectList.getDefault().setMainProject(project1);
+        } catch (IllegalArgumentException e) {
+            exceptionThrown = true;
+        }
+        
+        assertTrue("IAE thrown when trying to set main project that is not opened", exceptionThrown);
+    }
     // helper code
 
     private static class MySubprojectProvider implements SubprojectProvider {
Index: projectuiapi/apichanges.xml
===================================================================
RCS file: /cvs/projects/projectuiapi/apichanges.xml,v
retrieving revision 1.18
diff -u -r1.18 apichanges.xml
--- projectuiapi/apichanges.xml	22 Aug 2005 20:47:45 -0000	1.18
+++ projectuiapi/apichanges.xml	25 Aug 2005 09:01:02 -0000
@@ -76,6 +76,20 @@
 
     <changes>
         
+        <change id="getSetMainProject">
+            <api name="general"/>
+            <summary>Ability to get and set main project</summary>
+            <version major="1" minor="11"/>
+            <date day="29" month="7" year="2005"/>
+            <author login="jlahoda"/>
+            <compatibility addition="yes" binary="compatible" deletion="no" deprecation="no" modification="no" semantic="compatible" source="compatible">
+            </compatibility>
+            <description>
+                Added <code>getMainProject</code> and <code>setMainProject</code> methods to OpenProjects.
+            </description>
+            <issue number="58461"/>
+        </change>
+        
         <change id="delete-copy-move-support">
             <api name="general"/>
             <summary>Project Delete/Copy/Rename/Move Support Added, Support for Default Project Delete/Copy/Rename/Move Added</summary>
Index: projectuiapi/nbproject/project.properties
===================================================================
RCS file: /cvs/projects/projectuiapi/nbproject/project.properties,v
retrieving revision 1.12
diff -u -r1.12 project.properties
--- projectuiapi/nbproject/project.properties	22 Aug 2005 20:47:45 -0000	1.12
+++ projectuiapi/nbproject/project.properties	25 Aug 2005 09:01:02 -0000
@@ -9,7 +9,7 @@
 # Code is Sun Microsystems, Inc. Portions Copyright 1997-2005 Sun
 # Microsystems, Inc. All Rights Reserved.
 
-spec.version.base=1.10.0
+spec.version.base=1.11.0
 is.autoload=true
 javadoc.title=Project UI API
 javadoc.arch=${basedir}/arch.xml
Index: projectuiapi/src/org/netbeans/api/project/ui/OpenProjects.java
===================================================================
RCS file: /cvs/projects/projectuiapi/src/org/netbeans/api/project/ui/OpenProjects.java,v
retrieving revision 1.5
diff -u -r1.5 OpenProjects.java
--- projectuiapi/src/org/netbeans/api/project/ui/OpenProjects.java	15 Dec 2004 10:36:29 -0000	1.5
+++ projectuiapi/src/org/netbeans/api/project/ui/OpenProjects.java	25 Aug 2005 09:01:02 -0000
@@ -102,6 +102,39 @@
         trampoline.closeAPI (projects);
     }
 
+    /**Retrieves the current main project set in the IDE.
+     *
+     * <div class="nonnormative">
+     * <p><strong>Warning:</strong> the set of usecases that require invoking this method is
+     * limited. {@link org.netbeans.spi.project.ui.support.MainProjectSensitiveActions} should
+     * be used in favour of this method if possible. In particular, this method should not
+     * be used to let user choose if an action should be run over main or current project.</p>
+     * </div>
+     *
+     * @return the current main project or null if none
+     * @since 1.11
+     */
+    public Project getMainProject() {
+        return trampoline.getMainProject();
+    }
+    
+    /**Sets the main project.
+     *
+     * <div class="nonnormative">
+     * <p><strong>Warning:</strong> the set of usecases that require invoking this method is
+     * very limited and should be generally avoided if possible. In particular, this method
+     * should not be used to set project created by the New Project Wizard as main.</p>
+     * </div>
+     *
+     * @param project project to set as main project (must be open), or
+     *                <code>null</code> to set no project as main.
+     * @throws IllegalArgumentException if the project is not opened.
+     * @since 1.11
+     */
+    public void setMainProject(Project project) throws IllegalArgumentException {
+        trampoline.setMainProject(project);
+    }
+    
     /**
      * Adds a listener to changes in the set of open projects.
      * As this class is a singleton and is not subject to garbage collection,
Index: projectuiapi/src/org/netbeans/modules/project/uiapi/OpenProjectsTrampoline.java
===================================================================
RCS file: /cvs/projects/projectuiapi/src/org/netbeans/modules/project/uiapi/OpenProjectsTrampoline.java,v
retrieving revision 1.3
diff -u -r1.3 OpenProjectsTrampoline.java
--- projectuiapi/src/org/netbeans/modules/project/uiapi/OpenProjectsTrampoline.java	15 Dec 2004 10:36:29 -0000	1.3
+++ projectuiapi/src/org/netbeans/modules/project/uiapi/OpenProjectsTrampoline.java	25 Aug 2005 09:01:02 -0000
@@ -32,4 +32,8 @@
     
     public void removePropertyChangeListenerAPI( PropertyChangeListener listener );
     
+    public Project getMainProject();
+    
+    public void setMainProject(Project project);
+    
 }