[Rev 01] RFR: 8242489: ChoiceBox: initially toggle not sync'ed to selection

[Jeanette Winzenburg]

On Thu, 16 Apr 2020 09:05:12 GMT, Jeanette Winzenburg <fastegal at openjdk.org> wrote:

>> modules/javafx.controls/src/main/java/javafx/scene/control/skin/ChoiceBoxSkin.java line 416:
>> 
>>> 415:                 } else {
>>> 416:                     toggleGroup.selectToggle(null);
>>> 417:                 }
>> 
>> The `else` part here means that user programmatically has selected a `Separator` or `SeparatorMenuItem`. The behavior
>> in such scenario is not defined in doc but the methods, `select()`, `selectNext()`, `selectPrevious()`  of
>> `ChoiceBox.ChoiceBoxSelectionModel` imply that if index points to a `Separator` then a valid item should be selected.
>> However these method do handle this correctly.  If these methods are implemented such that no Separator is allowed to
>> be selected then this `else` part would not be needed and we might be able to remove the `instanceof` checks.  The fix
>> in this PR looks good to me. But we should also decide the behavior in above scenario and may be file a JBS. If we
>> decide that when a `Separator` is chosen for selection then the current selection should not be changed or a valid item
>> should be selected, then the test related to Separator selection need to be changed. Or all of it can be handled in a
>> follow on issue.
>
> yeah, you are right:
> 
> a) the implementation of ChoiceBoxSelectionModel is broken when it comes to handling of unselectable items (such as
> Separator): next/previous try to move on, the others simply select. The implementation changed in fix of
> [JDK-8088261](https://bugs.openjdk.java.net/browse/JDK-8088261) - before select(index) tried to handle it, after this
> was moved into next/previous. Arguably, the model can do what it wants without specification ;)  b) the skin is
> responsible to sync the selection state of its toggles with the state of model: if the selectedIndex/Item does not have
> a corresponding toggle (f.i. if it's a separator), all toggles must be unselected.   c) my test related to the
> Separator is broken - as you correctly noted, it will fail if a future implementation decides to select a really
> selectable item :)   My plan:
> 1. do nothing for a (don't feel like filing yet another bug around selection ;) and b (the skin behaves correctly, I
> think) 2. fix the test to be resistant against implementation changes of selectionModel
> 
> Thanks for the extensive review, very much appreciated :)

btw: just noticed that there are methods in ChoiceBoxSkin testing the fix for next/prev

    @Test public void test_jdk_8988261_selectNext() {
    @Test public void test_jdk_8988261_selectPrevious() {

the name look like they want to point to the corresponding issue .. but the id is incorrect: that id doesn't exist,
should be 8088261 (spelling error, I think) - is it okay to change them to the right id?

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PR: https://git.openjdk.java.net/jfx/pull/177