Bug 298835 Merge e4 Project Path Variable back into the 3.6 stream
The virtual folder and filters changes are already in 3.6, the project path variable changes in e4 still remains to be merged.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/internal/ide/dialogs/PathVariablesGroup.java
* @return boolean the enabled state of the group's widgets.
     * 	 <code>true</code> if called prior to calling <code>createContents</code>.
     */
    public boolean getEnabled() {
        if (variableTable != null && !variableTable.isDisposed()) {
            return variableTable.getEnabled();
        }
        return true;
    }
    /**
     * Returns the selected variables.
     *  
     * @return the selected variables. Returns an empty array if 
     * 	the widget group has not been created yet by calling 
     * 	<code>createContents</code>
     */
    public PathVariableElement[] getSelection() {
        if (variableTable == null) {
            return new PathVariableElement[0];
        }
        TableItem[] items = variableTable.getSelection();
        PathVariableElement[] selection = new PathVariableElement[items.length];
        for (int i = 0; i < items.length; i++) {
            String name = (String) items[i].getData();
            selection[i] = new PathVariableElement();
            selection[i].name = name;
            selection[i].path = (IPath) tempPathVariables.get(name);
        }
        return selection;
    }