[jfx26] RFR: 8373936: RichEditorDemoApp enhancements

[Kevin Rushforth]

On Wed, 28 Jan 2026 22:51:47 GMT, Andy Goryachev <angorya at openjdk.org> wrote:

> Backport of the following change:
> 
> [JDK-8376138](https://bugs.openjdk.org/browse/JDK-8376138) RichTextArea: getModelStyleAttrs might return wrong attributes

LGTM. And Skara confirms that it is a clean backport.

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Marked as reviewed by kcr (Lead).

PR Review: https://git.openjdk.org/jfx/pull/2057#pullrequestreview-3719674814