How to keep CategoryTree stayed opened after going back?

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When I am going down in one category and subcategories (depth 5-6), after

loading the specified category and then hitting the "back" button on the

browser , the category tree is folded again. Is there any chance the tree stays

opened? Please reply ASAP... How to keep nodes expaneded even after

clicking back button in browser.Any code changes to be done in Categorytree

extension?