/// <summary>
        /// This method is called when the preview button is clicked
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void ButtonPreview_Click(object sender, RoutedEventArgs e)
        {
            debugLogger.LogMessage(actualLeftPath, actualRightPath, "ButtonPreview_Click()", "User clicked on preview button");

            if (!ShowSync())
                return;

            bool leftDirectoryAccessible = IsDirectoryAccessible(actualLeftPath);
            bool rightDirectoryAccessible = IsDirectoryAccessible(actualRightPath);
            if (leftDirectoryAccessible && rightDirectoryAccessible)
            {
                if (!settingsManager.IsFoldersLocked())
                {
                    EnableInterface(false);
                    previewSync = new Preview();
                    previewSync.LeftPath = actualLeftPath;
                    previewSync.RightPath = actualRightPath;
                    previewSync.ExcludeData = settingsManager.LoadExcludeData(actualLeftPath, actualRightPath);
                    previewSync.backgroundWorkerForPreview.RunWorkerCompleted += new RunWorkerCompletedEventHandler(backgroundWorkerForPreview_RunWorkerCompleted);
                    previewSync.PreviewSync();

                    // Updates UI
                    LabelProgress.Visibility = Visibility.Visible;
                    LabelProgress.Content = MESSAGE_PREPARING_FOLDERS;
                }
            }
            else
            {
                string rightsString = nsync.Properties.Resources.accessRightsInsufficient;
                if (!leftDirectoryAccessible)
                    rightsString += "\n" + ShortenPath(actualLeftPath, 50);
                if (!rightDirectoryAccessible)
                    rightsString += "\n" + ShortenPath(actualRightPath, 50);
                helper.Show(rightsString, HELPER_WINDOW_HIGH_PRIORITY, HelperWindow.windowStartPosition.windowTop);
                LabelProgress.Content = MESSAGE_ERROR_DETECTED;
                LabelProgress.Visibility = Visibility.Visible;
            }
        }