How do you make an object/tool appear under Plone on the left navigation frame in the ZMI?

I开发者_StackOverflow中文版 would like my object to show up under the Plone site on the left navigation frame in the ZMI. Could not find an obvious way to do this. How can I accomplish this?

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I think your object needs to be folderish to appear on the left frame.

Try adding isPrincipiaFolderish = True as a class variable.