Collapsible vertical menu

Looking for a Joomla add-on

[HSteck]

I'm new to CMSs, and leaning heavily toward Joomla. I'm looking for an add-on that takes a (vertical / sidebar) menu like this...

-------------------------

Item 1 
 Item 1.1 
  Item 1.1.1 
  Item 1.1.2 
  Item 1.1.3 
   Item 1.1.3.1 
   Item 1.1.3.2 
  Item 1.1.4 
 Item 1.2 
 Item 1.3 
Item 2 
 Item 2.1 
  Item 2.1.1 
 Item 2.2 
Item 3 
 Item 3.1 
Item 4 

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... and collapses it down to show only the main level plus whatever other levels are the "parent" levels of the current page being viewed. For example, if you are viewing the page linked by "Item 2.1.1," then the menu would look like this:

-------------------------

Item 1 
Item 2 
 Item 2.1 
  Item 2.1.1 
 Item 2.2 
Item 3 
Item 4 

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I've been searching through the different add-ons for Joomla, and so far I haven't found something that does this. Does this functionality come packaged with some templates? (Perhaps showing my ignorance here.) Is there a site where I should be looking for such an add-on?

Is there another section on this forum better suited for this question?

Any help will be appreciated.