RFR: 8263807: Button types of a DialogPane are set twice, returns a wrong button

[Marius Hanl]

On Mon, 5 Apr 2021 22:58:47 GMT, Kevin Rushforth <kcr at openjdk.org> wrote:

>> When DialogPane#getButtonTypes().setAll() is called twice with the same argument(s), DialogPane#lookupButton does not return the node which is shown inside the button bar.
>> This is due DialogPane adding two list change listeners to 'buttons' (#getButtonTypes). They have the wrong order, which will result in the button bar not changing at all and the 'buttonNodes' list will recreate the dialog button(s).
>> Finally, this will make DialogPane#lookupButton returning the 'wrong' button, which is in fact not used inside the dialog button bar.
>
> modules/javafx.controls/src/main/java/javafx/scene/control/DialogPane.java line 1062:
> 
>> 1060:         boolean hasDefault = false;
>> 1061:         for (ButtonType cmd : getButtonTypes()) {
>> 1062:             Node button = buttonNodes.get(cmd);
> 
> Why was this change needed?

This change is not needed for the fix. 

I removed it, because #computeIfAbsent() isn't needed anymore.
The (now) first listener will run and create/remove buttons based off the changes to #getButtonTypes().
The second listener (which is calling this method) will use all created buttons (to put them inside the ButtonBar).

-> So only a simple #get() is needed.
#computeIfAbsent() basically masked this bug before, as it was also creating a button, if missing. But as mentionend, when we are here, all buttons should be already created by the first listener.

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PR: https://git.openjdk.java.net/jfx/pull/432