Gif images sometimes have black backgrounds

[HeikoKlare]

Description
The backgrounds of Gif images somestimes become black. This is probably somehow related to the transparency pixel of those images.

Issue was originally reported here:

• Eclipse 2025-06: UI rendering issues on Windows with monitors using different scale factors eclipse-platform/eclipse.platform.swt#2494

Reproduction
Reproduction description can be found in this comment: eclipse-platform/eclipse.platform.swt#2494

Expected Behavior
Backgrounds of Gif images should become black.
It would probably make sense to create a simple SWT snippet based on Gifs and the described workflow first for easy reproduction and debugging.

[HeikoKlare]

Increasing priority to high as we face this issue in our product as well.

[ShahzaibIbrahim]

I am able to reproduce the issue with simple gif image with this concrete snippet: (Primary: 100, Secondary: 125). Background is lost when moving to 100 -> 125 and back.

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


public class ButtonWithGifImage {
    public static void main(String[] args) {
    	System.setProperty("swt.autoScale.updateOnRuntime", "true");
        Display display = new Display();
        Shell shell = new Shell(display);
        shell.setText("SWT Button with GIF Image");
        shell.setSize(300, 200);

        Button button = new Button(shell, SWT.PUSH);
        button.setBounds(80, 60, 140, 60);
        button.setText("Click Me");

        Image image = new Image(display,
            ButtonWithGifImage.class.getResourceAsStream("sample.gif"));
        button.setImage(image);

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

        image.dispose();
        display.dispose();
    }
}

After moving back and forth, the result: