[Windows] item in Combo will be selected when using up and down arrow

[jdneo]

Important

If you are reporting a crash on Linux, please check if webkit is mentioned in the crash file.
If yes, please try to set WEBKIT_DISABLE_COMPOSITING_MODE=1 and/or WEBKIT_DISABLE_DMABUF_RENDERER=1 environment variables.
If they prevent crashes, don't report the bug please, it is already known as #843

Describe the bug
On Windows, when expand a combo, and use up or down arrow to navigate through, the item will be selected after click up or down arrow

To Reproduce

combo-issue.zip

1. Download the attached project
2. Import into Eclipse
3. Launch it
4. Open the custom view
5. Expand the combo
6. Press down arrow

Expected behavior
The item should only be selected when enter is pressed, or clicked by mouse

Screenshots

combo_issue.mp4

Environment:

1. Select the platform(s) on which the behavior is seen:

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

2. Additional OS info (e.g. OS version, Linux Desktop, etc)

Edition Windows 11 Enterprise
Version 25H2
Installed on ‎2024/‎10/‎17
OS build 26200.6899
Experience Windows Feature Experience Pack 1000.26100.253.0

3. JRE/JDK version

Version since
Eclipse or SWT version since when the behavior is seen [e.g. 4.23]

Workaround (or) Additional context
MacOS does not have this issue.

[Phillipus]

I can confirm this. This doesn't happen on Mac.

widgetSelected is called when the keyboard up and down arrow keys are pressed. This should only be called when pressing Enter or mouse selection.

Is this a recent change in Windows or has it always been like this?

Here's a stand-alone snippet to reproduce it:

package swt;

import org.eclipse.swt.SWT;
import org.eclipse.swt.events.SelectionEvent;
import org.eclipse.swt.events.SelectionListener;
import org.eclipse.swt.layout.FillLayout;
import org.eclipse.swt.widgets.Combo;
import org.eclipse.swt.widgets.Display;
import org.eclipse.swt.widgets.Shell;

public class ComboTest {
    
    public static void main(String[] args) {
        final Display display = new Display();

        final Shell shell = new Shell(display);
        shell.setText("Combo Test");
        shell.setLayout(new FillLayout());
        shell.setSize(600, 400);
        
        Combo combo = new Combo(shell, SWT.READ_ONLY);
        combo.setItems("Item 1", "Item 2", "Item 3", "Item 4", "Item 5", "Item 6");
        combo.select(0);
        
        combo.addSelectionListener(new SelectionListener() {
            @Override
            public void widgetSelected(SelectionEvent e) {
                System.out.println("widgetSelected");
            }
            
            @Override
            public void widgetDefaultSelected(SelectionEvent e) {
                System.out.println("widgetDefaultSelected");
            }
        });
        
        shell.open();

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

        display.dispose();
    }
}

[HeikoKlare]

If am not mistaken, it has ever been like this.

The Combo behaviors of the different OSes are quite different. See also this issue with the MacOS combo:

• [macOS] Combo erroneously reports no selection index #2191

Would be interesting to see how Linux behaves in this case.

[Phillipus]

If am not mistaken, it has ever been like this.

Thanks. I guess I never noticed it, or only used the mouse to select.