ScalaFX: how to wrap text in a TableCell

Question

I want to show a list of key and values in a TreeTableView, and some of the values are a bit longer text which I want to wrap around and show completely.

I thought I use TextFieldTreeTableCell with wrapText and vgrow as follows:

 val valCol = new TreeTableColumn[(String,String), String] {
      text = "Header"
      cellValueFactory = { p => StringProperty(p.value.value.value._2) }
      cellFactory = { p => new TextFieldTreeTableCell[(String,String),String]() {
        wrapText = true
        vgrow = Priority.Always
      } }
    }

But the text is only shown in one line wiht ... at the end.

What am I missing?