8366201: RichTextArea: remove allowUndo parameter

[andy-goryachev-oracle]

Original user feedback (see https://mail.openjdk.org/pipermail/openjfx-discuss/2025-August/000267.html ) called for adding an allowUndo parameter to applyStyle() and setStyle() methods similarly to replaceText().

Upon further analysis, the allowUndo parameter was a mistake: allowing the application code to disable creating undo/redo entries messes up the internal undo/redo stack.
There is an internal need (UndoableChange), but it should not be exposed via public API.

This PR also adds isUndoRedoEnabled() and setUndoRedoEnabled() to the StyledTextModel, as well as its forwarding aliases to RichTextArea to allow for the application to disable undo/redo temporarily, for example, when building a document from multiple segments.

WARNING this is an incompatible change, permitted because of the incubator.

There remains a possible issue with currently unlimited size of the undo/redo stack - perhaps we should limit its depth to maybe 100-200 entries, see https://bugs.openjdk.org/browse/JDK-8370447 .

/reviewers 2
/csr

---

Progress

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Issue

• JDK-8366201: RichTextArea: remove allowUndo parameter (Enhancement - P4)

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[bridgekeeper]

👋 Welcome back angorya! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

[openjdk]

❗ This change is not yet ready to be integrated.
See the Progress checklist in the description for automated requirements.

[openjdk]

@andy-goryachev-oracle has indicated that a compatibility and specification (CSR) request is needed for this pull request.

@andy-goryachev-oracle please create a CSR request for issue JDK-8366201 with the correct fix version. This pull request cannot be integrated until the CSR request is approved.

[openjdk]

@andy-goryachev-oracle an approved CSR request is already required for this pull request.

[andy-goryachev-oracle]

/reviewers 2

[openjdk]

@andy-goryachev-oracle
The total number of required reviews for this PR (including the jcheck configuration and the last /reviewers command) is now set to 2 (with at least 1 Reviewer, 1 Author).

[mlbridge]

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• 01: Full - Incremental (84d02951)
• 00: Full (4103d954)

[kevinrushforth]

This will also need a csr.

/csr

[kevinrushforth]

This will also need a csr.

Ah, and I see you already marked it as such

[openjdk]

@kevinrushforth an approved CSR request is already required for this pull request.

[kevinrushforth]

I agree that having this as a per-method argument doesn't make sense.

I think it's worth considering a future enhancement to add a property to enable or disable the undo feature, with a default of true. When set to true, it stores entries in the undo stack and enables undo/redo. When set to false, it discards the current stack and doesn't store anything or allow undo/redo until the next time it is set to true.

[andy-goryachev-oracle]

Thank you @kevinrushforth for suggesting the enableUndo (enableUndoRedo ?) property.

Consider a scenario of building a (large) document programmatically: in the absence of such a property, the undo entries will be created, consuming the resources, to be immediately discarded by clearUnoRedo() at the end, as suggested earlier. A better solution is to indeed explicitly disable the undo/redo via a new property. This is especially helpful when we consider that currently the undo/redo stack has no limit - see also https://bugs.openjdk.org/browse/JDK-8370447 .

Converting this PR back to Draft to add the property, since the code is interdependent and we'll need a CSR anyway.