Just noticed that it is possible to deselect the sole selected item in single selection mode. A discussion with our test users resulted in a concensus that least users actually expect that it is possible to have nothing selected at all in a SINGLE selection mode (while this might make sense in MULTIPLE selection mode).

Hence, we want to propose that in a future release of JavaFX there should be an additional flag which could be used with either mode, SINGLE and MULTIPLE: boolean preventEmptySelection().

What the flag does is to prevent removal of the last item of the selection, hence a selection will always contain at least one item. To guarantee this, the flag also will add the very first item (index 0) to the selection as soon as data gets available.