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Undo/Redo (Text Editors)

XenoAtom.Terminal.UI provides a lightweight undo/redo system for text editors built on TextEditorBase / TextEditorCore.

Supported controls

Undo/redo is available in:

  • TextBox
  • TextArea
  • MaskedInput
  • NumberBox<T>
  • Custom controls deriving from TextEditorBase

Key bindings

  • Undo: Ctrl+Z
  • Redo: Ctrl+R

Note: some terminals remap or intercept certain key combinations. If a key binding does not reach the app, remap it in your terminal.

Behavior

  • Undo/redo records document edits (insert, delete, newline, backspace join, paste, selection replace).
  • Undo/redo also restores the editor selection/caret state for a consistent experience.
  • Find/Replace integration:
    • Replace is undoable.
    • Replace All is recorded as a single undo step.

Coalescing (typing runs)

Typing is coalesced into larger undo steps when possible (so you can undo a “typing run” instead of one character at a time). Coalescing is reset by operations like paste, selection replacement, and some cursor/selection changes.

Configuration

TextEditorBase exposes:

  • EnableUndo (default: true)
  • MaxUndoEntries (default: 200)
  • CanUndo / CanRedo (bindable state)
  • Undo() / Redo()
  • ClearUndoHistory()

Example:

new TextArea("Hello\nWorld")
    .EnableUndo(true)
    .MaxUndoEntries(500);

When history is cleared

Undo history is cleared when:

  • EnableUndo is set to false
  • the editor is bound to a different document
  • the document is edited outside of the editor’s edit pipeline (for example, by calling ITextDocument methods directly)

If you perform external document updates and still want undo/redo, route changes through the editor control (or provide a higher-level edit API that records undo entries).