CTabFolder: support circular page traversal in MRU mode without chevron

[fedejeanne]

What

Fixes eclipse-platform/eclipse.platform.ui#4135

CTabFolder.onPageTraversal now supports circular keyboard page traversal when setMRUVisible(true) is enabled and all tabs fit without a chevron:

• Pressing Ctrl+PageDown (SWT.TRAVERSE_PAGE_NEXT) on the last tab now wraps around to the first tab.
• Pressing Ctrl+PageUp (SWT.TRAVERSE_PAGE_PREVIOUS) on the first tab now wraps around to the last tab.

Previously, in MRU mode with no chevron shown, traversing past the last/first tab had no effect at all (selection stayed put).

This only affects the MRU branch of onPageTraversal. The non-MRU path already wrapped correctly via modulo arithmetic, so its behavior is unchanged. The chevron behavior is intentionally preserved: if there are more tabs than fit and the chevron is shown, traversing past the last/first visible tab still opens the chevron drop-down list exactly as before.

How to test

1. Run Snippet395 (added in examples/org.eclipse.swt.snippets), which creates a CTabFolder with setMRUVisible(true) and 4 tabs that all fit without a chevron.
2. Give the CTabFolder focus (click a tab) and select the last tab, then press Ctrl+PageDown: it should now wrap to the first tab.
3. Select the first tab and press Ctrl+PageUp: it should now wrap to the last tab.
4. Resize the window (make it narrower) so that the chevron appears (more tabs than fit), and confirm this PR preserves the original behavior: traversing past the last/first visible tab opens the chevron drop-down list instead of wrapping around.

Files changed

• bundles/org.eclipse.swt/Eclipse SWT Custom Widgets/common/org/eclipse/swt/custom/CTabFolder.java
• examples/org.eclipse.swt.snippets/src/org/eclipse/swt/snippets/Snippet395.java (new)

[github-actions]

Test Results

  200 files  ±0    200 suites  ±0   28m 3s ⏱️ +31s
4 744 tests ±0  4 720 ✅ ±0   24 💤 ±0  0 ❌ ±0 
6 892 runs  ±0  6 724 ✅ ±0  168 💤 ±0  0 ❌ ±0 

Results for commit 0186ea6. ± Comparison against base commit c76abe1.

♻️ This comment has been updated with latest results.

[fedejeanne]

FTR I tested on Windows and Linux (using WSL) and it works es expected.

If someone could test it on Mac before Wednesday EOD then we can have it in M2.

[HeikoKlare]

I've tested on MacOS and it works as expected for me.

Regarding the snippet: if that is supposed to go into the codebase, it needs to be referenced in the Snippets.md and on the website snippets overview. I wonder if it wouldn't be even better to just extend the CTabFolder tab of the CustomControlExample with an option to activate MRU, as it would allow to test even more combinations easily (I just did when testing this PR) and can in general be more widely used than a quite case-specific snippet.

[eclipse-platform-bot]

This pull request changes some projects for the first time in this development cycle.
Therefore the following files need a version increment:

examples/org.eclipse.swt.examples/META-INF/MANIFEST.MF

An additional commit containing all the necessary changes was pushed to the top of this PR's branch. To obtain these changes (for example if you want to push more changes) either fetch from your fork or apply the git patch.

Git patch

From b919c02a45d31c478825518494981fd0a05e5192 Mon Sep 17 00:00:00 2001
From: Eclipse Platform Bot <platform-bot@eclipse.org>
Date: Tue, 21 Jul 2026 12:06:58 +0000
Subject: [PATCH] Version bump(s) for 4.41 stream


diff --git a/examples/org.eclipse.swt.examples/META-INF/MANIFEST.MF b/examples/org.eclipse.swt.examples/META-INF/MANIFEST.MF
index b7b9968fa3..c078217c52 100644
--- a/examples/org.eclipse.swt.examples/META-INF/MANIFEST.MF
+++ b/examples/org.eclipse.swt.examples/META-INF/MANIFEST.MF
@@ -2,7 +2,7 @@ Manifest-Version: 1.0
 Bundle-ManifestVersion: 2
 Bundle-Name: %plugin.SWTStandaloneExampleSet.name
 Bundle-SymbolicName: org.eclipse.swt.examples; singleton:=true
-Bundle-Version: 3.109.100.qualifier
+Bundle-Version: 3.109.200.qualifier
 Bundle-Vendor: %providerName
 Bundle-Localization: plugin
 Bundle-RequiredExecutionEnvironment: JavaSE-21
-- 
2.54.0

Further information are available in Common Build Issues - Missing version increments.

[fedejeanne]

Thank you for reviewing @HeikoKlare ! I removed the new snippet and added a new option to the CTabFolder tab of the CustomControlExample instead.

The fix can be verified by setting the property to true: