From d1ce54b513ba46f35b1fd56d674148f04da2ae56 Mon Sep 17 00:00:00 2001
From: Mathias Jakobsen <mathias.jakobsen@overleaf.com>
Date: Tue, 14 Apr 2026 11:12:21 +0100
Subject: [PATCH] Merge pull request #32794 from overleaf/mj-tab-scroll

[web] Allow scrolling with wheel in tab container

GitOrigin-RevId: af81825288387675bdac5d734041299126d3b44c
---
 .../components/tabs/tabs-container.tsx        |  9 +++++
 .../source-editor/components/tabs.spec.tsx    | 34 ++++++++++++++++++-
 2 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/services/web/frontend/js/features/source-editor/components/tabs/tabs-container.tsx b/services/web/frontend/js/features/source-editor/components/tabs/tabs-container.tsx
index 0fee481727..3415027eb7 100644
--- a/services/web/frontend/js/features/source-editor/components/tabs/tabs-container.tsx
+++ b/services/web/frontend/js/features/source-editor/components/tabs/tabs-container.tsx
@@ -59,6 +59,14 @@ export const TabsContainer = () => {
     setHovered(false)
   }, [throttledOnDragOver])
 
+  const onWheel = useCallback((e: React.WheelEvent) => {
+    if (e.deltaY !== 0 && e.deltaX === 0) {
+      // if this is a purely vertical scroll, convert it to a horizontal scroll
+      // instead
+      e.currentTarget.scrollLeft += e.deltaY
+    }
+  }, [])
+
   return (
     <div className="editor-tabs-container">
       <div
@@ -69,6 +77,7 @@ export const TabsContainer = () => {
         onDragOver={onDragOver}
         onDrop={onDrop}
         onDragLeave={onDragLeave}
+        onWheel={onWheel}
         tabIndex={-1}
       >
         {tabs.map(tab => (
diff --git a/services/web/test/frontend/features/source-editor/components/tabs.spec.tsx b/services/web/test/frontend/features/source-editor/components/tabs.spec.tsx
index e47b46ea34..2075c83244 100644
--- a/services/web/test/frontend/features/source-editor/components/tabs.spec.tsx
+++ b/services/web/test/frontend/features/source-editor/components/tabs.spec.tsx
@@ -731,7 +731,7 @@ describe('File Tabs', function () {
     })
   })
 
-  describe('Tab scroll into view', function () {
+  describe('Tab scrolling', function () {
     it('scrolls the selected tab into view', function () {
       const manyDocs = [
         { _id: DOC_IDS.main, name: 'main.tex' },
@@ -761,6 +761,38 @@ describe('File Tabs', function () {
 
       cy.findByRole('tab', { name: /main\.tex/ }).should('be.visible')
     })
+
+    it('scrolls horizontally on vertical mouse wheel', function () {
+      const manyDocs = [
+        { _id: DOC_IDS.main, name: 'main.tex' },
+        ...Array.from({ length: 10 }, (_, i) => ({
+          _id: `ch${i + 1}`,
+          name: `chapter-${i + 1}.tex`,
+        })),
+      ]
+      const rootFolder = makeRootFolder(manyDocs)
+      mountTabs({ rootFolder })
+
+      // Open enough tabs to cause overflow
+      cy.then(() => selectDoc(DOC_IDS.main))
+      for (let i = 1; i <= 10; i++) {
+        const id = `ch${i}`
+        cy.then(() => selectEntity(makeDocEntity(id, `chapter-${i}.tex`)))
+      }
+
+      // Scroll back to the start
+      cy.findByRole('tablist').then($el => {
+        $el[0].scrollLeft = 0
+      })
+
+      // Trigger a vertical wheel event on the tablist
+      cy.findByRole('tablist').trigger('wheel', { deltaY: 100, deltaX: 0 })
+
+      // scrollLeft should have increased
+      cy.findByRole('tablist').should($el => {
+        expect($el[0].scrollLeft).to.be.greaterThan(0)
+      })
+    })
   })
 
   describe('SplitTestBadge', function () {