Bug with input events from within collage

[jvoigtlaender]

The following doesn't work as it supposedly should:

import Graphics.Input exposing (..)
import Graphics.Collage exposing (..)
import Graphics.Element exposing (..)
import Signal exposing (..)
import Color exposing (..)

mbx = mailbox ()

foo = move (40,0) (toForm (clickable (message mbx.address ()) <| show "foo"))

counter = foldp (\_ -> (+) 1) 0 mbx.signal

-- Given the above, clicking on the "foo" text should always increment the counter.

bar1 = toForm (show "bar")
bar2 = outlined (solid black) (circle 5)

-- However, this doesn't work:

main = (\c -> flow down [ show c
                        , collage 150 20 [foo, bar2]
                        ]) <~ counter

-- Strangely enough, after replacing [foo, bar2] by any of
-- [foo, bar1], [bar1, foo], [bar2, foo], it does work.

More discussion on this happened on the mailing list and in elm/compiler#747.

The issue is not specific to clickable, for example it also appears with button.

Mentioning elm-lang/core#332 so folks can find this more easily.