public override void Run()
        {
            // Get WixExtensionFolderNode.
            WixExtensionFolderNode folderNode = GetWixExtensionFolderNode();

            if (folderNode == null)
            {
                return;
            }

            // Display file dialog.
            using (OpenFileDialog fileDialog = CreateOpenFileDialog()) {
                if (DialogResult.OK == fileDialog.ShowDialog(WorkbenchSingleton.MainForm))
                {
                    // Add files to project.
                    WixProject project = ((WixProject)folderNode.Project);
                    project.AddWixExtensions(fileDialog.FileNames);
                    project.Save();
                }
            }

            // Refresh project browser.
            folderNode.Refresh();
            folderNode.Expanding();
            folderNode.Expand();
        }