TYPO3 Core

I can confirm this. The same problem exists in TYPO3 v4.7.
The suggested fix works for me, too.

Could you provide a more detailed description how to test/reproduce this?

I guess it also occurs in 6.0, even if the code looks completely different there

Test TypoScript:

page = PAGE

temp.mailform = FORM
temp.mailform {
  dataArray {
    20.label = Foobar
    20.type = test=select
    20.valueArray {
      10.label = Blue
      10.value = 1
      20.label = Red
      20.value = 2
      20.selected = 1
    }
  }
  recipient = info@example.com
  layout = <div class="some-class">###LABEL### ###FIELD###</div>
}

page.10 < temp.mailform

Patch set 2 for branch master has been pushed to the review server.
It is available at https://review.typo3.org/20282

Patch set 1 for branch TYPO3_6-1 has been pushed to the review server.
It is available at https://review.typo3.org/22751

Patch set 1 for branch TYPO3_6-0 has been pushed to the review server.
It is available at https://review.typo3.org/22752