SWT DateTime (GTK) traps TAB traversal inside widget causing infinite internal focus cycling (day/month/year), no TRAVERSE_TAB_NEXT emitted

[HugoFB]

Description
When using org.eclipse.swt.widgets.DateTime on GTK (Linux), the widget consumes TAB key events internally instead of propagating them as SWT traversal events.

As a result, focus never leaves the control and TAB navigation loops between internal fields (day → month → year).

This behavior does not occur on Windows.

Environment

• • All OS
• • Windows
• • Linux
• • macOS

SWT: 3.133.0 (Eclipse 4.39)
Java: OpenJDK 25.0.3
OS: Ubuntu 26.04
Desktop: MATE
Windowing system: X11
GTK: 3.24.52
Locale: es_ES.UTF-8

(and tests in Ubuntu 26.04 Gnome and swt 3.134.0)

Steps To Reproduce

import org.eclipse.swt.SWT;
import org.eclipse.swt.layout.GridData;
import org.eclipse.swt.layout.GridLayout;
import org.eclipse.swt.widgets.*;

public class DateTimeTabDebug {
    public static void main(String[] args) {

        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setLayout(new GridLayout(2, false));

        new Label(shell, SWT.NONE).setText("Text 1:");
        Text t1 = new Text(shell, SWT.BORDER);
        t1.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));

        new Label(shell, SWT.NONE).setText("Date:");
        DateTime dt = new DateTime(shell, SWT.DATE | SWT.DROP_DOWN | SWT.BORDER);
        dt.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));

        new Label(shell, SWT.NONE).setText("Text 2:");
        Text t2 = new Text(shell, SWT.BORDER);
        t2.setLayoutData(new GridData(SWT.FILL, SWT.CENTER, true, false));

        shell.pack();
        shell.open();

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

        display.dispose();
    }
}

javac --release 25 \
  -cp org.eclipse.swt.gtk.linux.x86_64-3.133.0.jar \
  DateTimeTabDebug.java

java \
  -cp .:org.eclipse.swt.gtk.linux.x86_64-3.133.0.jar \
  DateTimeTabDebug

Actual Behavior
When pressing TAB:

Focus moves from Text1 → DateTime correctly
Inside DateTime:

• TAB cycles through internal fields (day → month → year)
• Focus never leaves the widget
• No focusLost event is generated
• No TRAVERSE_TAB_NEXT is received

Debug output shows repeated:

[FILTER TRAVERSE] widget=DateTime detail=0 doit=true
[DATE TRAVERSE] detail=0 doit=true

(detail=0 corresponds to SWT.TRAVERSE_NONE)

The event is repeated indefinitely.

Expected behavior
Pressing TAB inside DateTime should:

• Move focus to next control (Text2)
• Generate SWT.TRAVERSE_TAB_NEXT
• Trigger focusLost on DateTime

Same behavior as on Window
A clear and concise description of what you expected to happen.

Observed Impact

• Keyboard navigation is broken on GTK
• Focus becomes trapped inside DateTime
• Cross-platform inconsistency (Windows vs Linux)
• No reliable workaround using standard SWT listeners

Additional Notes

• TraverseListener is triggered but only with SWT.TRAVERSE_NONE (detail=0)
• KeyListener does not reliably receive TAB before GTK consumes it
• Issue reproducible in minimal SWT application
• Likely related to GTK DateTime internal editing of sub-fields

Request

Please confirm whether this is:

• a known limitation of SWT GTK DateTime, or
• a regression in SWT GTK event translation layer

and whether there is a recommended workaround or fix planned.