Closure Scope not captured? — Coffeescript

Okay, I don't know how to phrase the title for this question.

openDir = (path) ->
socket.emit "get_metadata", path, (data) ->
    columnBox = $ "<div/>", class: "columnbox"
    for item in data.contents
        itemBox = $ "<div/>", class: "itembox"
        itemBox.click ->
            columnBox_inner.children().removeClass "selected"
            itemBox.addClass "selected" # <<<--- Over here
            openDir item.path
        columnBox.append itemBox
    columnBox.appendTo "#columnscontainer"

I understand that the variable itemBox is defined under openDir's scope here. But since the pointed out line is in a lambda function, shouldn't itemBox there capture the object referenced by itemBox of the parent scope instead of getting mutated to the last object referenced by it?

To put it clearly, I expect the click handler of each itemBox to perform addClass "selected" to itself. But what happens is that itemBox in each of the click handlers always refer to the last itemBox.

I can easily fix this by changing where itemBox gets declared. i.e. changing

for item in data.contents

into

data.contents.forEach (item) ->

But I'd like to know why the lambda function does not capture the variables current value.