@Override
  public void setSelected(final AnActionEvent e, final boolean isSelected) {
    final VirtualFile[] selectedFiles = getSelectedFiles();
    assert selectedFiles.length != 0;

    final ContentEntryEditor contentEntryEditor = myEntryTreeEditor.getContentEntryEditor();
    for (VirtualFile selectedFile : selectedFiles) {
      final SourceFolder sourceFolder = contentEntryEditor.getSourceFolder(selectedFile);
      if (isSelected) {
        if (sourceFolder == null) { // not marked yet
          contentEntryEditor.addSourceFolder(selectedFile, myEditTestSources, "");
        } else {
          if (myEditTestSources != sourceFolder.isTestSource()) {
            final String packagePrefix = sourceFolder.getPackagePrefix();
            contentEntryEditor.removeSourceFolder(sourceFolder);
            contentEntryEditor.addSourceFolder(selectedFile, myEditTestSources, packagePrefix);
          }
        }
      } else {
        if (sourceFolder != null) { // already marked
          contentEntryEditor.removeSourceFolder(sourceFolder);
        }
      }
    }
  }