Well, an accordion category plugin would be fairly easy, i could do that.. i ll try to find some time this week, if i dont remind me..

Meantime you can use alternative solution like mtree categories if that works for you..

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This will do the job also. But I have no idea where find "mtree" categories". It's a plugin? Something elsewhere?
Thanks
Mel

Yep, Afwas did this back in 2.x days and it still works, but its not listed in plugins dir i think.

You can get it here: http://www.tilqi.com/assets/collapsable_categories_plugin.zip