The safest way to keep Slack hidden during a Teams call is also the most obvious: share only the specific window you need, not your entire desktop. Microsoft documents this clearly — select Share → Window, pick your PowerPoint or browser, and Teams will broadcast only that application.
This works perfectly until your workflow demands otherwise. Until you need to switch between three apps during a demo. Until a priority Slack message breaks through Do Not Disturb. Until you Alt-Tab and the taskbar preview shows "Slack — Your Boss: We need to talk."
Here's how to close those gaps.
Step 1: Share a Window, Not Your Desktop
In Teams, click Share → Window. Select the exact app you want to show. This is free, built-in, and effective for simple presentations.
The failure mode: If you accidentally click "Screen" instead of "Window," or if you need to show multiple apps and switch between them, you're now sharing your entire display surface. Anything visible on that monitor — including background windows — is broadcast.
Step 2: Pause Slack Notifications
In Slack, click your profile picture → Pause notifications → select a duration. This stops banners and sounds.
The failure mode: Priority messages from specific people can still break through. And pausing notifications doesn't hide Slack itself — it only hides the popup. If you switch to Slack while sharing your desktop, the conversation is visible.
Step 3: Enable Windows Do Not Disturb
Windows 11 Focus Assist (Do Not Disturb) suppresses most system notifications. Turn it on before the meeting.
The failure mode: It doesn't suppress Slack's in-app unread badges, taskbar flashes, or window titles. And again, it does nothing if you're sharing your desktop and accidentally expose the Slack window.
Step 4: Technical Cloaking (The Deterministic Fix)
If you regularly share your desktop or switch apps during presentations, you need a tool that removes Slack from the capture stream entirely.
Free Option: WinHider
GitHub: aamitn/winhider
Install: winget install winhider
WinHider applies WDA_EXCLUDEFROMCAPTURE to Slack and removes it from the taskbar/Alt-Tab. It's free and Microsoft Store-verified.
Limitation: No notification shield. If a message arrives while you're presenting, Slack's internal notification sound still plays (if audio is shared), and the app icon may still flash.
Workflow Option: NoCapture
NoCapture cloaks Slack from capture and suppresses notification banners from protected apps. It also masks the window title in Alt-Tab and taskbar previews — so even if you slip and expose the switcher, viewers see "Untitled Application" instead of "Slack — Your Boss: We need to talk."
The live preview pane lets you verify exactly what Teams is capturing before you share. Set a "Client Demo" routine that auto-cloaks Slack, email, and your password manager when you start the meeting.
We wrote about why tab titles and metadata leak more than pixels here.
The "No Surprises" Checklist
Before every high-stakes presentation:
- [ ] Teams → Share → Window (not Screen)
- [ ] Slack → Pause notifications
- [ ] Windows → Do Not Disturb on
- [ ] NoCapture (or WinHider) → Cloak Slack, email, password manager
- [ ] NoCapture → Open Live Preview, verify capture stream
- [ ] Alt-Tab once to confirm taskbar titles are masked
Why This Matters
The most expensive screen-share leaks aren't caused by negligence. They're caused by the gap between what you think is visible and what the capture API actually sees. Your attention is on the presentation. The capture stream is indifferent to your attention.
Manual preparation is probabilistic. Technical cloaking is deterministic. The difference is between "I hope I didn't miss anything" and "I know exactly what the capture contains."
NoCapture provides OS-level window cloaking, title masking, and notification shielding for Windows. Free for two windows. Because "being careful" isn't a strategy.
