[GTK3] images are cropped and/or not displayed in Tree with SWT.VIRTUAL

[zkxvh]

Describe the bug
Images in a tree with SWT.VIRTUAL often displayed as cropped or not shown at all.

Example 1:
Start the snippet below and press the following buttons: [2,1], then [3,2] and finally [1,0].
This is what I get: image for [3,2] is cropped, image for [1,0] isn't shown:

Example 2:
Start the snippet below and do the following:

1. press button [32,1]
2. scroll the content of the tree down to show [32,1]
3. press buttons [33,2] and [31,0]

This is what I get: images for [31,0], [32,1] and [33,2]are cropped:

To Reproduce

import org.eclipse.swt.SWT;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

public class SetImage_TreeVirtual {

	private Display display;
	private Shell shell;
	private Composite buttonBox;
	private Tree tree;

	private Image[][] images = new Image[50][3];

	public static void main (String[] args) {
		new SetImage_TreeVirtual ().run ();
	}

	void run () {
		display = new Display ();
		shell = new Shell (display);
		shell.setText (getClass ().getSimpleName ());
		shell.setLayout (new GridLayout ());

		buttonBox = new Composite (shell, 0);
		buttonBox.setLayout (new FillLayout ());
		createSetImageButton (1, 0, 20, display.getSystemColor (SWT.COLOR_RED));
		createSetImageButton (2, 1, 40, display.getSystemColor (SWT.COLOR_GREEN));
		createSetImageButton (3, 2, 60, display.getSystemColor (SWT.COLOR_BLUE));

		buttonBox = new Composite (shell, 0);
		buttonBox.setLayout (new FillLayout ());
		createSetImageButton (31, 0, 20, display.getSystemColor (SWT.COLOR_CYAN));
		createSetImageButton (32, 1, 40, display.getSystemColor (SWT.COLOR_BLACK));
		createSetImageButton (33, 2, 60, display.getSystemColor (SWT.COLOR_MAGENTA));

		tree = new Tree (shell, SWT.VIRTUAL);
		tree.setHeaderVisible (true);
		tree.setLayoutData (new GridData (GridData.FILL_BOTH));
		for (int i = 1; i <= 3; i++) {
			var column = new TreeColumn (tree, SWT.LEFT);
			column.setText ("Column " + i);
			column.setWidth (200);
		}

		tree.addListener (SWT.SetData, e -> {
			TreeItem item = (TreeItem) e.item;
			var row = tree.indexOf (item);
			for (var col = 0; col < 3; col++) {
				item.setText (col, "[" + row + "," + col + "]");
				item.setImage (col, images[row][col]);
			}
		});
		tree.setItemCount (50);

		shell.setSize (700, 600);
		shell.open ();

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

	private void createSetImageButton (int row, int col, int imageSize, Color imageColor) {
		var button = new Button (buttonBox, SWT.PUSH);
		var image = createImage (imageSize, imageColor);
		button.setImage (image);
		button.setText ("[" + row + "," + col + "]");
		button.addListener (SWT.Selection, e -> {
			images[row][col] = (images[row][col] == null) ? image : null;
			tree.clear (row, false);
		});
	}

	private Image createImage (int imageSize, Color color) {
		var image = new Image (display, imageSize, imageSize);
		var gc = new GC (image);
		gc.setForeground (color);
		gc.setBackground (display.getSystemColor (SWT.COLOR_WHITE));
		gc.setLineWidth (5);
		gc.fillRectangle (0, 0, imageSize, imageSize);
		gc.drawRectangle (0, 0, imageSize - 1, imageSize - 1);
		gc.dispose ();
		return image;
	}
}

Expected behavior
Images should be shown and should not be cropped.

Screenshots
See above.

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)
   Ubuntu 24.04.1 LTS
   Windowing System x11
   X.Org version: 21.1.11
   XFCE 4.18
   GTK 3.24.41

3. JRE/JDK version
   OpenJDK 64-Bit Server VM (build 17.0.13+11-Ubuntu-2ubuntu124.04, mixed mode, sharing)

Version since
SWT 4.964

Workaround (or) Additional context
Sometimes the snippet may crash because of #678

[deepika-u]

Hi, I am also seeing the same issue with below environment.

Environment
Description: Ubuntu 24.04 LTS
XDG_SESSION_TYPE=wayland

Eclipse SDK
Version: 2025-03 (4.35)
Build id: I20250108-1800
OS: Linux, v.6.8.0-51-generic, x86_64 / gtk 3.24.41
Java vendor: Oracle Corporation
Java runtime version: 23+36-2368
Java version: 23

Let me try your pr now.