void hiddened() {
   PreferenceStore prefs = frame.getPreferences();
   prefs.setValue(PREFS_SAME_TARGET_KEY, sameTargetCheck.getSelection());
   prefs.setValue(PREFS_USE_EXTENSION_FILTER_KEY, extFilterCheck.getSelection());
   prefs.setValue(PREFS_EXTENSION_FILTER_KEY, extFilterText.getText());
   if (prefs.getBoolean(PREFS_TARGET_FILES_KEY + ".save")) // $NON-NLS-1$
   prefs.setValue(
         PREFS_TARGET_FILES_KEY, fileEntryListToText(targetFileListViewer.getExtPathList()));
   if (prefs.getBoolean(PREFS_SOURCE_FILES_KEY + ".save")) // $NON-NLS-1$
   prefs.setValue(
         PREFS_SOURCE_FILES_KEY, fileEntryListToText(storageFileListViewer.getExtPathList()));
 }
 List<String> getExtStorageFileList() {
   return sameTargetCheck.getSelection()
       ? getExtTargetFileList()
       : storageFileListViewer.getExtPathList();
 }
 List<String> getExtTargetFileList() {
   return targetFileListViewer.getExtPathList();
 }