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[macOS] StyledText: an arrow key during Korean IME composition discards the composing syllable instead of committing it

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Evaluación

Dificultad
4/5
Tiempo estimado
3-5 días
Aptitud para principiantes
46/100
Tipo de issue
Error
Claridad
Bien especificado
Estado de actividad
Activo
Stack tecnológico
java, macos
Área
desktop, frontend

Línea de trabajo

Start by comparing how StyledText handles arrow-key input during Korean IME composition with the plain Text widget, using the reproduction in the issue on macOS with the 2-Set Korean input source. The issue also points to #2412 as a potentially related case. Done means the composing syllable is committed before the caret moves, rather than being discarded.

Escrito por el modelo de indexación a partir del texto del issue.

Descripción

Describe the bug

On macOS, an arrow key pressed while the Korean IME is composing discards the composing syllable instead of committing it. The character is lost outright — it never reaches the widget's text, and there is no undo path back to it.

A plain Text in the same application commits it correctly on the same keystrokes, so this is specific to StyledText.

To Reproduce

This snippet puts a StyledText above a Text so the two can be compared in one run. Each readout prints what that widget's own text model holds.

import org.eclipse.swt.SWT;
import org.eclipse.swt.custom.StyledText;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Label;
import org.eclipse.swt.widgets.Shell;
import org.eclipse.swt.widgets.Text;

public class StyledTextKoreanArrow {

    public static void main(String[] args) {
        final Display display = new Display();
        final Shell shell = new Shell(display);
        shell.setLayout(new GridLayout(1, false));

        new Label(shell, SWT.NONE).setText("StyledText");
        final StyledText styled = new StyledText(shell, SWT.BORDER);
        styled.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
        final Label styledReadout = new Label(shell, SWT.NONE);
        styledReadout.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
        Runnable refreshStyled =
                () -> styledReadout.setText(describe(styled.getText(), styled.getCaretOffset()));
        refreshStyled.run();
        styled.addModifyListener(e -> refreshStyled.run());
        styled.addCaretListener(e -> refreshStyled.run());

        new Label(shell, SWT.NONE).setText("Text (single line)");
        final Text text = new Text(shell, SWT.BORDER | SWT.SINGLE);
        text.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
        final Label textReadout = new Label(shell, SWT.NONE);
        textReadout.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));
        Runnable refreshText =
                () -> textReadout.setText(describe(text.getText(), text.getCaretPosition()));
        refreshText.run();
        text.addModifyListener(e -> refreshText.run());
        text.addListener(SWT.KeyUp, e -> refreshText.run());

        shell.setSize(620, 320);
        shell.setText("SWT " + SWT.getVersion() + " — Korean IME arrow");
        shell.open();

        while (!shell.isDisposed()) {
            if (!display.readAndDispatch()) {
                display.sleep();
            }
        }
        display.dispose();
    }

    private static String describe(String content, int caret) {
        StringBuilder codePoints = new StringBuilder();
        content.codePoints().forEach(cp -> codePoints.append(String.format("U+%04X ", cp)));
        if (codePoints.length() == 0) {
            codePoints.append("(empty)");
        }
        return "text: \"" + content + "\"   caret: " + caret + "   " + codePoints;
    }
}

Select the macOS 2-Set Korean input source, then in each box:

  1. Type 가 나, then begin 다 and stop. It stays underlined — still composing.
  2. Press ← once.

StyledText after the arrow, with the composing syllable gone:

text: "가나"   caret: 2   U+AC00 U+B098

Text, same keystrokes, with it committed before the caret moved:

text: "가나다"   caret: 2   U+AC00 U+B098 U+B2E4

While composing, both widgets read "가나" and draw 다 underlined. That part is expected — the preedit is not in the text yet. The difference is what the arrow does with it: Text commits it, StyledText drops it.

Arrow presses after the first only move the caret, since there is no composition left to lose.

Expected behavior

An arrow key arriving during composition should commit the preedit and then move the caret, which is what Text does here and what native macOS controls do.

Screenshots

The readouts quoted above are the widgets' own getText() output rather than a description of the screen, so they carry the same evidence; happy to attach captures if that is easier to read.

Environment:

  1. Select the platform(s) on which the behavior is seen:
    • All OS
    • Windows
    • Linux
    • macOS
  1. Additional OS info (e.g. OS version, Linux Desktop, etc)

macOS 26.6.2, Apple Silicon. Input source: 2-Set Korean (한국어 두벌식).

  1. JRE/JDK version

Temurin 20.0.1 (aarch64).

Version since

Seen on SWT 3.130.0 (SWT.getVersion() reports 4969). Not bisected — downstream reports of the same symptom go back to 2020 (DBeaver 7.3 on macOS 10.14), so it is unlikely to be a recent regression.

Workaround (or) Additional context

No workaround beyond committing the syllable first — press Space and delete it, or switch the input source — before moving the caret.

Possibly the same root as #2412, which reports Backspace deleting one character too many in StyledText while the Korean IME is active: same widget, same platform, same input source, and also a key arriving mid-composition that is not reconciled against the marked text. Filed separately because the visible outcomes differ, but one fix for how StyledText treats a key press during composition may cover both.

Downstream this is dbeaver/dbeaver#10615, open since 2020 and labelled a third-party issue. The tracker linked there, bugs.eclipse.org 371397, no longer leads anywhere actionable — that report sits under the archived z_Archived product against the PDT component and the Carbon platform, so it is not tracking the SWT code this lives in. Raising it here so there is a live report against the right component.

Lenguaje dominante
Java
Estrellas
202
Forks
206
Merge medio
16 h 56 min
PR fusionados (30 d)
110

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