public void actionPerformed(AnActionEvent e) {
    final DataContext dc = e.getDataContext();
    if ((!isVisible(dc)) || (!isEnabled(dc))) return;

    final Project project = CommonDataKeys.PROJECT.getData(dc);
    final Iterable<Pair<VirtualFilePointer, FileStatus>> iterable =
        VcsDataKeys.UPDATE_VIEW_FILES_ITERABLE.getData(dc);
    final Label before = (Label) VcsDataKeys.LABEL_BEFORE.getData(dc);
    final Label after = (Label) VcsDataKeys.LABEL_AFTER.getData(dc);

    final String selectedUrl = VcsDataKeys.UPDATE_VIEW_SELECTED_PATH.getData(dc);

    ShowDiffAction.showDiffForChange(
        new MyIterableWrapper(iterable.iterator(), before, after),
        new MySelectionMarker(selectedUrl),
        project,
        new ShowDiffUIContext(true));
  }
 private boolean isVisible(final DataContext dc) {
   final Project project = CommonDataKeys.PROJECT.getData(dc);
   return (project != null)
       && (VcsDataKeys.LABEL_BEFORE.getData(dc) != null)
       && (VcsDataKeys.LABEL_AFTER.getData(dc) != null);
 }