Bug 125138 [LinkedResources] cannot extend variable
Using I20060118-0800 Using the contextual menu upon a project that has at least one linked source folder: - Build Path/Configure Build Path; - Source tab; - select a linked source folder, Edit; - Variables; - define CURRENT_WORKSPACE pointing to the current workspace root: - New; - Name: CURRENT_WORKSPACE; - Folder...: select the workspace root, then OK; - OK; - Extend: gets a 'No entries available'. I may miss a point here, but I believe this not correct. I would expect to be able to select a subdirectory of my current workspace. Pointing the variable to a Java project root doesn't seem to help.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/dialogs/PathVariableSelectionDialog.java
private static final int EXTEND_ID = IDialogConstants.CLIENT_ID + 1;
    private PathVariablesGroup pathVariablesGroup;
    private int variableType;
    /**
     * Creates a path variable selection dialog.
     *
     * @param parentShell the parent shell
     * @param variableType the type of variables that are displayed in 
     * 	this dialog. <code>IResource.FILE</code> and/or <code>IResource.FOLDER</code>
     * 	logically ORed together.
     */
    public PathVariableSelectionDialog(Shell parentShell, int variableType) {
        super(parentShell);
        setTitle(IDEWorkbenchMessages.PathVariableSelectionDialog_title);
        this.variableType = variableType;
        pathVariablesGroup = new PathVariablesGroup(false, variableType,
                new Listener() {
                    /* (non-Javadoc)
                     * @see org.eclipse.swt.widgets.Listener#handleEvent(org.eclipse.swt.widgets.Event)
                     */
                    public void handleEvent(Event event) {
                        updateExtendButtonState();
                    }