TextAreaState
Owner-thread mutable text and vertical scroll position for one multiline editor.
Accepted input is well-formed Unicode with LF line breaks. CRLF, CR, VT, FF, NEL, line separator, and paragraph separator normalize to LF before the UTF-16 length limit is applied. Other C0 controls, DEL, isolated surrogates, and the section-sign formatting marker are rejected without changing state. Values own no retained nodes; one live text observer prevents simultaneous editors from sharing this state. Reads, writes, observation, and subscription release are confined to the constructing thread.
Parameters
initialValue
initial text, normalized before storage.
Throws
when maxLength is not positive or initialValue is unsupported or too long after normalization.