Tabs Bug: Native HTML <select> elements close immediately when clicked inside macOS Teams client tabs #2920
Description
Summary
A new severe issue appears to break user experience with a recent update of the Mac OS native Teams client.
Native HTML <select> dropdowns inside Microsoft Teams tabs open and then immediately close on macOS Teams Desktop.
This makes all dropdowns and form controls effectively unusable for macOS users.
The dropdown functionality worked before on Mac OS native client. The issue also does not occur in Windows Teams Desktop or Teams Web.
Environment
- Product: Microsoft Teams Desktop native Client (macOS)
- Version: 25306.803.4086.7087
- OS: macOS
- Embedding: Web app as Microsoft Teams tab (iframe)
- Framework: Pure HTML + JavaScript (reproducible without any JS)
- Works correctly on:
- ✅ Teams Web (Edge / Chrome / Safari)
- ✅ Windows Teams Desktop
- ❌ macOS Teams Desktop (bug)
Steps to Reproduce
See video: https://www.loom.com/share/31bad2e233e04e118a6d7f8cd9088622
- Host a minimal HTML page:
<!DOCTYPE html> <html lang="en"> <body> <h3>Teams Dropdown Test</h3> <select> <option>Option A</option> <option>Option B</option> <option>Option C</option> </select> <p>Works fine in browsers and Windows Teams, fails on macOS Teams client.</p> </body> </html>
- Add this page as a Teams tab via manifest or the Developer Portal.
- Open the tab inside macOS Teams Desktop.
- Click the dropdown.
Actual Behavior
- The dropdown opens for a split second and immediately closes.
- No option can be selected.
blurandfocusoutevents fire instantly aftermousedown.- The iframe loses focus as if a click occurred outside the frame.
Expected Behavior
- The dropdown should remain open until a user selects an option or clicks elsewhere — same behavior as in:
- Windows Teams Desktop
- Teams Web (Edge / Chrome / Safari)
- Standalone Safari / Chrome on macOS
Technical Analysis
- Appears to be a WebView (WebKit) bug in the macOS Teams client.
The native<select>popover triggers ablurevent on the iframe window, causing immediate closure. - Happens even with empty HTML (no JavaScript, no CSS).
→ Confirms a Teams runtime issue, not developer code. - Focus restoration or event suppression (
preventDefault,stopImmediatePropagation) does not help.
Impact
- Affects all web apps embedded as Teams tabs that use native
<select>dropdowns or form elements. - Includes enterprise SaaS apps and no-code platforms (e.g. Bubble.io, Retool, custom internal tools).
- Breaks basic user interaction for macOS Teams users.
Severity / Priority
- 🚨 Critical / Urgent
- Blocks form usage in all web tabs on macOS Teams.
- Impacts third-party and enterprise Teams integrations at scale.
Additional Notes
- Verified across multiple macOS versions and Teams builds.
- Happens with and without JavaScript or external CSS.
- Replacing native
<select>with custom HTML menus resolves the issue — confirming that the problem is specific to native popover handling.
Request
Please escalate this to the macOS Teams runtime / WebView engineering team.
This is a fundamental usability regression that blocks all web-based dropdown interactions in Teams tabs on macOS.