RFR: 8351047: TitledPane should handle titles that are resizable

[John Hendrikx]

On Wed, 26 Mar 2025 20:13:25 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

>> Yeah, the reason I was hesitant to change this is that currently you can set the alignment from CSS in two ways:
>> 
>>      .titled-pane {
>>          -fx-alignment: RIGHT;
>>      }
>>      
>> Or:
>>  
>>     .titled-pane > .title {
>>          -fx-alignment: RIGHT;
>>     }     
>>     
>> Both will work at the moment.  I'm not sure which one is more correct.  
>> 
>> A titled pane naturally has two major regions; its title area, and its content area.  The top level alignment could apply to either or none in theory.  The top level alignment setting is "inherited" from being a Labeled control, which only has a single alignment to worry about (this also shows using this kind of inheritance is just a bad idea).  It would have been much more clear to have a `titleAlignment` and `contentAlignment` property.
>> 
>> At the "top" level there is nothing to align, since a titled pane always fill its width.
>
> the original code had some logic around `(pos == null)`, I wonder if we need to do the same here, that is, derive the effective alignment from both values?

That was just for deriving the `hpos` and `vpos` fields, which are no longer needed, in case `pos` was `null`.  The `null` check is now handled in `LabeledSkinBase`.

Of course we could think of some kind of derive option (how to derive LEFT + RIGHT?) or a way to remove one of these, but I think either way, it's outside the scope of this change.  I added the comment for future maintainers (I could have left it out, and we'd probably not be having this discussion).  

As it is, I don't think we should fix this as part of this change as it is really completely unrelated (and might need much more discussion and perhaps even a CSR...)

Perhaps I should remove the comment and instead we describe this in an issue?

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PR Review Comment: https://git.openjdk.org/jfx/pull/1742#discussion_r2015031232