[Win32] Add tool bar tests for items rendering their own icon

ToolBarWin32Tests guards against tool items rendering a wrong or blank
icon after a monitor zoom change. That defect is not specific to zoom
changes though: a tool bar addresses its normal, hot and disabled image
list with a single index per item, so any operation reassigning those
slots can make an item render another item's icon.

Adds tests covering that items keep rendering their own icon when
another item is disposed, when a second tool bar uses icons of the same
size and therefore shares the image lists, and after an orientation
change. Like the existing test, they observe the actual rendered result
via public API only and reuse its rendering and color classification.

Related to
#3466

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Author: HeikoKlare

bundles/org.eclipse.swt/Eclipse SWT Tests/win32/org/eclipse/swt/widgets/ToolBarWin32Tests.java

@@ -90,6 +90,129 @@ void testIconsRenderedCorrectlyAfterZoomChangeWithImageListHole() {
 		}
 	}
 
+	/**
+	 * A tool bar addresses its normal, hot and disabled image list with a single
+	 * index per item, and disposing an item frees its slot in those lists for
+	 * reuse. The remaining items must keep rendering their own icon.
+	 */
+	@Test
+	void testIconsRenderedCorrectlyAfterDisposingAnotherItem() {
+		Display display = new Display();
+		RGB[] colors = { new RGB(220, 40, 40), new RGB(40, 180, 40), new RGB(40, 40, 220) };
+		Image[] icons = createIcons(display, colors);
+		try {
+			Shell shell = new Shell(display);
+			shell.setLayout(new FillLayout());
+			ToolBar bar = new ToolBar(shell, SWT.FLAT);
+			ToolItem[] items = createItems(bar, icons);
+			shell.setSize(500, 90);
+			shell.open();
+
+			items[1].dispose();
+
+			Set<ToolItemWithExpectedColor> itemsToCheck = Set.of(
+					new ToolItemWithExpectedColor(items[0], colors[0]),
+					new ToolItemWithExpectedColor(items[2], colors[2]));
+			assertTrue(waitUntilIconsRenderOwnColor(display, () -> iconsRenderOwnColor(bar, itemsToCheck, colors),
+					TIMEOUT_MILLIS), "every tool item must render its own icon after another item is disposed");
+		} finally {
+			disposeAll(icons, display);
+		}
+	}
+
+	/**
+	 * Tool bars share the image lists for a given icon size, so the items of one
+	 * tool bar must not be affected by those of another tool bar using icons of the
+	 * same size.
+	 */
+	@Test
+	void testIconsRenderedCorrectlyWithSecondToolBarUsingSameIconSize() {
+		Display display = new Display();
+		RGB[] colors = { new RGB(220, 40, 40), new RGB(40, 180, 40), new RGB(40, 40, 220), new RGB(230, 200, 30) };
+		Image[] icons = createIcons(display, colors);
+		try {
+			Shell shell = new Shell(display);
+			shell.setLayout(new FillLayout(SWT.VERTICAL));
+			ToolBar firstBar = new ToolBar(shell, SWT.FLAT);
+			ToolItem[] firstItems = createItems(firstBar, icons[0], icons[1]);
+			ToolBar secondBar = new ToolBar(shell, SWT.FLAT);
+			ToolItem[] secondItems = createItems(secondBar, icons[2], icons[3]);
+			shell.setSize(500, 180);
+			shell.open();
+
+			Set<ToolItemWithExpectedColor> firstItemsToCheck = Set.of(
+					new ToolItemWithExpectedColor(firstItems[0], colors[0]),
+					new ToolItemWithExpectedColor(firstItems[1], colors[1]));
+			Set<ToolItemWithExpectedColor> secondItemsToCheck = Set.of(
+					new ToolItemWithExpectedColor(secondItems[0], colors[2]),
+					new ToolItemWithExpectedColor(secondItems[1], colors[3]));
+			assertTrue(
+					waitUntilIconsRenderOwnColor(display,
+							() -> iconsRenderOwnColor(firstBar, firstItemsToCheck, colors)
+									&& iconsRenderOwnColor(secondBar, secondItemsToCheck, colors),
+							TIMEOUT_MILLIS),
+					"every tool item must render its own icon although both tool bars share the image lists");
+		} finally {
+			disposeAll(icons, display);
+		}
+	}
+
+	/**
+	 * Changing the orientation moves every item's images into image lists created
+	 * for the new orientation, which must retain the assignment of items to their
+	 * icons.
+	 */
+	@Test
+	void testIconsRenderedCorrectlyAfterOrientationChange() {
+		Display display = new Display();
+		RGB[] colors = { new RGB(220, 40, 40), new RGB(40, 180, 40), new RGB(40, 40, 220) };
+		Image[] icons = createIcons(display, colors);
+		try {
+			Shell shell = new Shell(display);
+			shell.setLayout(new FillLayout());
+			ToolBar bar = new ToolBar(shell, SWT.FLAT);
+			ToolItem[] items = createItems(bar, icons);
+			shell.setSize(500, 90);
+			shell.open();
+
+			bar.setOrientation(SWT.RIGHT_TO_LEFT);
+			bar.setOrientation(SWT.LEFT_TO_RIGHT);
+
+			Set<ToolItemWithExpectedColor> itemsToCheck = new HashSet<>();
+			for (int i = 0; i < items.length; i++) {
+				itemsToCheck.add(new ToolItemWithExpectedColor(items[i], colors[i]));
+			}
+			assertTrue(waitUntilIconsRenderOwnColor(display, () -> iconsRenderOwnColor(bar, itemsToCheck, colors),
+					TIMEOUT_MILLIS), "every tool item must render its own icon after an orientation change");
+		} finally {
+			disposeAll(icons, display);
+		}
+	}
+
+	private static Image[] createIcons(Display display, RGB[] colors) {
+		Image[] icons = new Image[colors.length];
+		for (int i = 0; i < colors.length; i++) {
+			icons[i] = solidIcon(display, 16, colors[i]);
+		}
+		return icons;
+	}
+
+	private static ToolItem[] createItems(ToolBar bar, Image... icons) {
+		ToolItem[] items = new ToolItem[icons.length];
+		for (int i = 0; i < icons.length; i++) {
+			items[i] = new ToolItem(bar, SWT.PUSH);
+			items[i].setImage(icons[i]);
+		}
+		return items;
+	}
+
+	private static void disposeAll(Image[] icons, Display display) {
+		for (Image icon : icons) {
+			icon.dispose();
+		}
+		display.dispose();
+	}
+
 	private static boolean waitUntilIconsRenderOwnColor(Display display, BooleanSupplier condition,
 			long timeoutMillis) {
 		long deadline = System.currentTimeMillis() + timeoutMillis;