[GTK3] StyledText reports wrong text typing Chinese letters with Pinyin

[tmssngr]

Describe the bug If a selection in the StyledText is replaced with a Chinese letter entered using Chinese (Pinyin), no (replaced) text is reported by the SWT.ExtendedModify event.

To Reproduce

• install Pinyin keyboard:
  • Ubuntu: sudo apt install ibus-pinyin, Manjaro: sudo pacman -S ibus-pinyin
  • reboot the machine
  • in the GTK preferences, page Keyboard, add the Chinese (Pinyin) keyboard layout
• Run this snippet:

  
  import org.eclipse.swt.SWT;
  import org.eclipse.swt.custom.ST;
  import org.eclipse.swt.custom.StyledText;
  import org.eclipse.swt.layout.FillLayout;
  import org.eclipse.swt.widgets.Display;
  import org.eclipse.swt.widgets.Shell;

public class PinyinTest { public static void main(String[] args) { final Display display = new Display(); final Shell shell = new Shell(display); shell.setLayout(new FillLayout()); final StyledText st = new StyledText(shell, SWT.BORDER); st.addListener(ST.ExtendedModify, event -> { System.out.printf("%d %d, '%s'(%d)\n", event.start, event.end - event.start, event.text, event.text.length()); });

    shell.setSize(400, 300);
    shell.open();
    while (!shell.isDisposed()) {
        if (!display.readAndDispatch()) {
            display.sleep();
        }
    }
    display.dispose();
}

}

- keep the keyboard layout at *en*
- type `abc`
- select `b`
- type `d` (replacing b)
- you will see on the console

0 1, ''(0)
1 1, ''(0)
2 1, ''(0)
1 1, 'b'(1)
```

• select d
• change the keyboard layout to Chinese (Pinyin)
• type d1 (replacing d)
• you will see on the console

  0 1, ''(0)
  1 1, ''(0)
  2 1, ''(0)
  1 1, 'b'(1)
  1 1, ''(0)

  -> although d has been replaced, it was not reported in event.text this time

Expected behavior Replacing with a Chinese character also should report the replaced character(s).

Environment:

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

   • • [ ] All OS
   • • [ ] Windows
   • • [x] Linux
   • • [ ] macOS

2. Additional OS info (e.g. OS version, Linux Desktop, etc) Tried with Ubuntu 22.04 and Manjaro/Gnome (latest)

[tmssngr]

Even worse: at the time when the first edit related event SWT.Verify occurs, the selected character already has been magically replaced (st.getText() does not contain it any more). This looks like a serious bug of the StyledText control with Chinese (Pinyin) keyboard layout.

[tmssngr]

Workaround: use StyledTextContent's TextChangeListener instead of SWT.Verify, SWT.Modify or SWT.ExtendedModify if you want to get access to the replaced text, e.g. for implementing an undo-feature.