Fix CTabFolder topRight WRAP overflow triggering too aggressively

bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/CTabFolder.java

@@ -591,7 +591,7 @@ Rectangle[] computeControlBounds (Point size, boolean[][] position) {
 					rects[i].height = getControlHeight(ctrlSize);
 					rects[i].x = x;
 					rects[i].y = getControlY(size, rects, borderBottom, borderTop, i);
-				} else if (((alignment & (SWT.WRAP)) != 0 && ctrlSize.x < availableWidth)) {
+				} else if ((alignment & SWT.WRAP) != 0 && ctrlSize.x <= availableWidth) {
 					x -= ctrlSize.x;
 					rects[i].width = ctrlSize.x;
 					rects[i].height = getControlHeight(ctrlSize);
@@ -3924,7 +3924,7 @@ boolean updateTabHeight(boolean force){
 	gc.dispose();
 	if (fixedTabHeight == SWT.DEFAULT && controls != null && controls.length > 0) {
 		for (int i = 0; i < controls.length; i++) {
-			if ((controlAlignments[i] & SWT.WRAP) == 0 && !controls[i].isDisposed() && controls[i].getVisible()) {
+			if (!controls[i].isDisposed() && controls[i].getVisible()) {
 				int topHeight = controls[i].computeSize(SWT.DEFAULT, SWT.DEFAULT).y;
 				topHeight +=  renderer.computeTrim(CTabFolderRenderer.PART_HEADER, SWT.NONE, 0,0,0,0).height + 1;
 				tabHeight = Math.max(topHeight, tabHeight);

tests/org.eclipse.swt.tests.gtk/ManualTests/org/eclipse/swt/tests/gtk/snippets/Bug3138_CTabFolderWrapDiagnostic.java

@@ -0,0 +1,142 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Contributors to the Eclipse Foundation.
+ *
+ * This program and the accompanying materials
+ * are made available under the terms of the Eclipse Public License 2.0
+ * which accompanies this distribution, and is available at
+ * https://www.eclipse.org/legal/epl-2.0/
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *******************************************************************************/
+package org.eclipse.swt.tests.gtk.snippets;
+
+import org.eclipse.swt.SWT;
+import org.eclipse.swt.custom.CTabFolder;
+import org.eclipse.swt.custom.CTabItem;
+import org.eclipse.swt.graphics.Point;
+import org.eclipse.swt.layout.FillLayout;
+import org.eclipse.swt.layout.GridData;
+import org.eclipse.swt.layout.GridLayout;
+import org.eclipse.swt.widgets.Composite;
+import org.eclipse.swt.widgets.Display;
+import org.eclipse.swt.widgets.Group;
+import org.eclipse.swt.widgets.Label;
+import org.eclipse.swt.widgets.Shell;
+import org.eclipse.swt.widgets.Text;
+import org.eclipse.swt.widgets.ToolBar;
+import org.eclipse.swt.widgets.ToolItem;
+
+/**
+ * Diagnostic snippet for CTabFolder topRight WRAP overflow on GTK.
+ *
+ * Reproduces the issue where setTopRight(control, SWT.RIGHT | SWT.WRAP)
+ * wraps to a second row even when there is sufficient horizontal space.
+ * This particularly affects composites containing a Text widget (search field).
+ *
+ * Run this and observe:
+ * 1. Whether the toolbar+text renders inline or wrapped below the tabs
+ * 2. The computed sizes printed to stdout
+ * 3. Compare behavior with SWT.RIGHT only (no WRAP) vs SWT.RIGHT | SWT.WRAP
+ *
+ * See https://github.com/eclipse-platform/eclipse.platform.swt/issues/3138
+ */
+public class Bug3138_CTabFolderWrapDiagnostic {
+
+	public static void main(String[] args) {
+		Display display = new Display();
+		Shell shell = new Shell(display);
+		shell.setSize(800, 400);
+		shell.setText("Bug 3138 - CTabFolder WRAP Diagnostic");
+		shell.setLayout(new GridLayout(1, false));
+
+		// --- Case 1: SWT.RIGHT | SWT.WRAP (the problematic case) ---
+		createTestCase(shell, "SWT.RIGHT | SWT.WRAP", SWT.RIGHT | SWT.WRAP);
+
+		// --- Case 2: SWT.RIGHT only (works but never wraps) ---
+		createTestCase(shell, "SWT.RIGHT only", SWT.RIGHT);
+
+		shell.open();
+
+		// Log sizes after layout
+		shell.getDisplay().asyncExec(() -> {
+			System.out.println("=== Shell size: " + shell.getSize() + " ===");
+			System.out.println();
+		});
+
+		while (!shell.isDisposed()) {
+			if (!display.readAndDispatch())
+				display.sleep();
+		}
+		display.dispose();
+	}
+
+	private static void createTestCase(Composite parent, String label, int alignment) {
+		Group group = new Group(parent, SWT.NONE);
+		group.setText(label);
+		group.setLayout(new FillLayout());
+		group.setLayoutData(new GridData(SWT.FILL, SWT.FILL, true, true));
+
+		CTabFolder folder = new CTabFolder(group, SWT.BORDER);
+
+		// Create tabs similar to Eclipse views
+		for (int i = 1; i <= 3; i++) {
+			CTabItem item = new CTabItem(folder, SWT.CLOSE);
+			item.setText("Tab " + i);
+			Label content = new Label(folder, SWT.NONE);
+			content.setText("Content for tab " + i);
+			item.setControl(content);
+		}
+		folder.setSelection(0);
+
+		// Create topRight composite mimicking Eclipse view toolbar with search field
+		Composite topRight = new Composite(folder, SWT.NONE);
+		GridLayout gl = new GridLayout(2, false);
+		gl.marginHeight = 0;
+		gl.marginWidth = 0;
+		topRight.setLayout(gl);
+
+		// ToolBar with a few buttons
+		ToolBar toolbar = new ToolBar(topRight, SWT.FLAT);
+		for (int i = 0; i < 3; i++) {
+			ToolItem ti = new ToolItem(toolbar, SWT.PUSH);
+			ti.setText("B" + i);
+		}
+
+		// Text widget (search field) - this is the key contributor to inflated size
+		Text searchText = new Text(topRight, SWT.BORDER | SWT.SEARCH);
+		searchText.setMessage("Filter...");
+		searchText.setLayoutData(new GridData(100, SWT.DEFAULT));
+
+		folder.setTopRight(topRight, alignment);
+
+		// Diagnostic logging
+		parent.getDisplay().asyncExec(() -> {
+			if (topRight.isDisposed()) return;
+
+			Point topRightSize = topRight.computeSize(SWT.DEFAULT, SWT.DEFAULT);
+			Point toolbarSize = toolbar.computeSize(SWT.DEFAULT, SWT.DEFAULT);
+			Point textSize = searchText.computeSize(SWT.DEFAULT, SWT.DEFAULT);
+			Point textSize100 = searchText.computeSize(100, SWT.DEFAULT);
+
+			System.out.println("--- " + label + " ---");
+			System.out.println("  topRight.computeSize(DEFAULT,DEFAULT) = " + topRightSize);
+			System.out.println("  toolbar.computeSize(DEFAULT,DEFAULT)  = " + toolbarSize);
+			System.out.println("  text.computeSize(DEFAULT,DEFAULT)     = " + textSize);
+			System.out.println("  text.computeSize(100,DEFAULT)         = " + textSize100);
+			System.out.println("  folder.getSize()                      = " + folder.getSize());
+
+			// Compute what CTabFolder sees as available width
+			int folderWidth = folder.getSize().x;
+			int itemWidth = 0;
+			for (CTabItem item : folder.getItems()) {
+				itemWidth += item.getBounds().width;
+			}
+			System.out.println("  total tab item width                  = " + itemWidth);
+			System.out.println("  remaining width (folder - items)      = " + (folderWidth - itemWidth));
+			System.out.println("  topRight preferred vs remaining       = " + topRightSize.x
+					+ " vs " + (folderWidth - itemWidth));
+			System.out.println("  WOULD OVERFLOW?                       = " + (topRightSize.x >= (folderWidth - itemWidth)));
+			System.out.println();
+		});
+	}
+}

tests/org.eclipse.swt.tests/JUnit Tests/org/eclipse/swt/tests/junit/Test_org_eclipse_swt_custom_CTabFolder.java

@@ -435,6 +435,87 @@ public void test_childControlOverlap() {
 	setTopRightAndCheckOverlap.accept(null, 0);
 }
 
+/**
+ * Test that a topRight control with SWT.RIGHT | SWT.WRAP renders inline
+ * when there is sufficient horizontal space, and wraps to a second row
+ * when space is tight. Verifies that the control is not clipped vertically
+ * when inline (tab row must grow to accommodate taller controls like Text).
+ *
+ * See https://github.com/eclipse-platform/eclipse.platform.swt/issues/3138
+ */
+@Test
+public void test_topRightWrapOverflow() {
+	makeCleanEnvironment(SWT.BORDER);
+	shell.setSize(800, 400);
+	shell.setLayout(new FillLayout());
+
+	for (int i = 1; i <= 3; i++) {
+		CTabItem item = new CTabItem(ctabFolder, SWT.CLOSE);
+		item.setText("Tab " + i);
+		Label content = new Label(ctabFolder, SWT.NONE);
+		content.setText("Content " + i);
+		item.setControl(content);
+	}
+	ctabFolder.setSelection(0);
+
+	// Create a topRight composite with a ToolBar and a Text (search field),
+	// similar to Eclipse view toolbars (e.g., EGit Staging View)
+	Composite topRight = new Composite(ctabFolder, SWT.NONE);
+	GridLayout gl = new GridLayout(2, false);
+	gl.marginHeight = 0;
+	gl.marginWidth = 0;
+	topRight.setLayout(gl);
+
+	ToolBar toolbar = new ToolBar(topRight, SWT.FLAT);
+	for (int i = 0; i < 3; i++) {
+		ToolItem ti = new ToolItem(toolbar, SWT.PUSH);
+		ti.setText("B" + i);
+	}
+	Text searchText = new Text(topRight, SWT.BORDER | SWT.SEARCH);
+	searchText.setMessage("Filter...");
+	searchText.setLayoutData(new GridData(80, SWT.DEFAULT));
+
+	ctabFolder.setTopRight(topRight, SWT.RIGHT | SWT.WRAP);
+
+	SwtTestUtil.openShell(shell);
+	processEvents();
+
+	// With 800px shell, there is plenty of space — topRight must be inline
+	Rectangle topRightBounds = topRight.getBounds();
+	CTabItem firstTab = ctabFolder.getItem(0);
+	Rectangle tabBounds = firstTab.getBounds();
+
+	// topRight should be on the same row as the tabs (y positions overlap)
+	assertTrue(topRightBounds.y < tabBounds.y + tabBounds.height,
+			"topRight should be on the same row as tabs when there is enough space. "
+			+ "topRight.y=" + topRightBounds.y + " tab.bottom=" + (tabBounds.y + tabBounds.height));
+
+	// topRight must not be clipped: its full height should be visible within the folder
+	Rectangle folderBounds = ctabFolder.getBounds();
+	assertTrue(topRightBounds.y >= 0,
+			"topRight must not be clipped at the top. topRight.y=" + topRightBounds.y);
+	assertTrue(topRightBounds.y + topRightBounds.height <= folderBounds.height,
+			"topRight must not be clipped at the bottom");
+
+	// Now shrink the shell so there is not enough space — topRight should wrap
+	int totalTabWidth = 0;
+	for (CTabItem item : ctabFolder.getItems()) {
+		totalTabWidth += item.getBounds().width;
+	}
+	int topRightWidth = topRight.computeSize(SWT.DEFAULT, SWT.DEFAULT).x;
+	// Make shell narrow enough that tabs + topRight don't fit
+	shell.setSize(totalTabWidth + topRightWidth / 2, 400);
+	processEvents();
+
+	topRightBounds = topRight.getBounds();
+	tabBounds = ctabFolder.getItem(0).getBounds();
+
+	// topRight should now be below the tab row (wrapped)
+	assertTrue(topRightBounds.y >= tabBounds.y + tabBounds.height,
+			"topRight should wrap below tabs when space is tight. "
+			+ "topRight.y=" + topRightBounds.y + " tab.bottom=" + (tabBounds.y + tabBounds.height));
+}
+
 /**
  * Min/max and chevron icon can appear below tab row.
  * Test for bug 499215, 533582.