I asked a question before: How to use IKImagebrowserView's group dispaly?
And now I am got the group style view very well, like this
when I select some photos(not all of them) from group yazi,
and then click the small triangle to collapse it, and click again to expand it, the selection is lost. I think it's the default action of IKImageBrowserView. Anyone knows what function will be called when I do the collapse/expand function.