Currently, selection change events are fired only when an explicit call has been made that affects the selection. For example, in ListView, calling either setSelectedRanges() or clearSelection() will fire this event. However, an operation that indirectly changes the selection state (such as adding or removing an item from the ListView's model data) does not trigger an event. This was originally done by design - selectedRangesChanged() includes the previous selection as an argument, and we didn't want to have to manually re-construct that every time the selection changed as a side effect of a model change:
public void selectedRangesChanged(ListView listView, Sequence<Span> previousSelectedRanges);
However, in practice, working within this model can be challenging. More than once I have registered a selection change listener expecting to receive notification of all selection changes, forgetting that it is not designed that way. I'm guessing that other developers may be confused by this as well.
So, I am proposing that components that maintain a selection state also fire selection change events when the selection changes indirectly. In this case, a null value would be passed for the previous selection. This will save the effort of re-constructing the previous selection info and will give the listener additional information about the nature of the change (i.e. null == indirect state change).
This change should also be propagated to TextInput, which has a similar issue with character change events. Currently, TextInput fires character change events via TextInputCharacterListener and text change events via TextInputTextListener. The textChanged() event does not pass the previous text value, which is inconsistent with other change events. textChanged() should be incorporated into TextInputCharacterListener and should pass the previous text value when it is changed via an explicit call to setText(); otherwise, it should pass null.
The updated version of TextArea should probably follow the same approach.