Added Html.Keyed to fix display bug reported here: https://github.com/elm-lang/virtual-dom/issues/24

CheckboxDisplayBugFix.elm

module Main exposing (..)

import Html exposing (..)
import Html.Keyed as Keyed
import Html.Events exposing (..)
import Html.Attributes exposing (..)
import Html.App as App


main : Program Never
main =
    App.beginnerProgram
        { model = init
        , update = update
        , view = view
        }


type alias Model =
    List Todo


type alias Todo =
    { completed : Bool
    , id : Int
    }


init : Model
init =
    [ Todo False 1
    , Todo False 2
    , Todo False 3
    ]


type Msg
    = SetCompleted Int
    | NoOp


update : Msg -> Model -> Model
update msg model =
    case msg of
        SetCompleted target ->
            let
                updateStatus todo =
                    if target == todo.id then
                        Todo True todo.id
                    else
                        todo
            in
                model |> List.map updateStatus

        NoOp ->
            model


view : Model -> Html Msg
view model =
    div []
        [ text "Added Html.Keyed which fixes the bug reported in https://github.com/elm-lang/virtual-dom/issues/24"
        , br [] []
        , text "Check items 1 or 2, the next item now correctly displays unchecked:"
        , div []
            (model
                |> List.filter (not << .completed)
                |> List.map viewItem
            )
        , text <| toString model
        ]


viewItem : Todo -> Html Msg
viewItem todo =
    Keyed.node "div"
        []
        [ ( (toString todo.id)
          , input
                [ type' "checkbox"
                , checked todo.completed
                , onCheck
                    (\on ->
                        if on then
                            SetCompleted todo.id
                        else
                            NoOp
                    )
                ]
                []
          )
        , ( (toString todo.id), text <| toString todo.id )
        ]

Elm v0.17.1. Run this code using elm reactor instead of in Try Elm since Try Elm it doesn't import Html.Keyed (as of 10/5/16).