Hi,
Finally I didn't use a class to flag the item. IMO, a class should be used only to define a style and besides it would have required way too many changes in mktree.js.
I added a global javascript variable "mktree_remember", that defaults to false, to be set in the head block before loading mktree.js. The difference now is that the "remember" flag is not set on a per-node basis but on a per-page one. I think it's a minor issue though given the use of mktree in the toolkit.
I've committed at oacs-5-4 branch.
