The problem shows itself in two ways:

1) After showing a dialog with a headerText, set the text to something longer
2) After showing a resizable dialog with a headerText, make the dialog smaller

=> The graphic (if visible) will be hidden. The header text does not get wrapped and will be partially concealed. It also doesn't behave like a Label and show "..." where it is cut off.

My use case is, that I am trying to use the headerText and graphics feature of Dialog to display validation messages, depending on user input (think of a wizard, with a little field validation). So imho:
- The graphic should always be visible on the right side
- The text should wrap at first (depending on the font-size, maybe 2 or 3 lines). If it exceeds its maximum space, it should behave like a Label and display "..." where the text is cut of and give the user the possibility to view the whole text while hovering of the Label.

btw: Looking at the source, I would have expected the headerLabel to wrap, since headerLabel.setWrapText(true); is called in DialogPane Line 965.