public Object getData(String dataId) {
    if (myTreeBrowser != null && myTreeBrowser.isVisible()) {
      return null;
    }
    if (PlatformDataKeys.NAVIGATABLE.is(dataId)) {
      if (mySelectedFile == null || !mySelectedFile.isValid()) return null;
      return new OpenFileDescriptor(myProject, mySelectedFile);
    } else if (PlatformDataKeys.VIRTUAL_FILE_ARRAY.is(dataId)) {
      return getVirtualFileArray();
    } else if (VcsDataKeys.IO_FILE_ARRAY.is(dataId)) {
      return getFileArray();
    } else if (PlatformDataKeys.TREE_EXPANDER.is(dataId)) {
      if (myGroupByChangeList) {
        return myTreeBrowser != null ? myTreeBrowser.getTreeExpander() : null;
      } else {
        return myTreeExpander;
      }
    } else if (VcsDataKeys.UPDATE_VIEW_SELECTED_PATH.is(dataId)) {
      return mySelectedUrl;
    } else if (VcsDataKeys.UPDATE_VIEW_FILES_ITERABLE.is(dataId)) {
      return myTreeIterable;
    } else if (VcsDataKeys.LABEL_BEFORE.is(dataId)) {
      return myBefore;
    } else if (VcsDataKeys.LABEL_AFTER.is(dataId)) {
      return myAfter;
    }

    return super.getData(dataId);
  }
  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 isEnabled(final DataContext dc) {
   final Iterable<Pair<VirtualFilePointer, FileStatus>> iterable =
       VcsDataKeys.UPDATE_VIEW_FILES_ITERABLE.getData(dc);
   return iterable != null;
 }