Hidden from the screen you share

Taking minutes has an awkward failure mode. You are sharing your screen, you press the shortcut to note something down, and the whole call watches you type “John is going to miss this deadline again”.

Jot’s floating windows - the capture box, the meeting pill and the save confirmation - are now hidden from screen capture by default. You see them; the share does not.

One call

Windows has had a way to do this since Windows 10 version 2004:

SetWindowDisplayAffinity(hwnd, WDA_EXCLUDEFROMCAPTURE)

A window with that affinity is drawn on your monitor as normal and left out of anything that captures the screen through the desktop duplication and graphics capture paths - which is what Teams, Zoom, OBS, the Snipping Tool and Win + Shift + S use. Before 2004, the same flag behaves like the older WDA_MONITOR and shows a black rectangle instead, which still hides the content, just less gracefully.

It is a property of the window, not a style bit, so in principle it is set once and survives being shown and hidden. Jot reapplies it on every show anyway, for a reason that the first hour on Windows taught the hard way: a transparent window lost one of its extended styles the first time it was actually shown, and the app had shipped that bug in every build. Reasserting on show is cheap. Trusting a one-time setup call was not.

Keeping it inside the budget

The capture box has a 100ms budget from keypress to a typeable window, and reading a setting from the database on every show is a cost it does not need. The “hide from screen sharing” setting is read at startup and whenever it changes in Settings, and cached in memory. The show path reads a boolean.

It is a setting, and it defaults on

It defaults on because the failure it prevents is embarrassing and silent - you do not find out until someone mentions it. But it is a setting, in Settings → Capture → Hide from screen sharing, because there are good reasons to turn it off:

• Demonstrating Jot to someone over a call.
• Taking your own screenshots of it. The flag hides it from those too, which also means anyone preparing Store or marketing images of the real app has to switch it off first.

What is not proven

This has been compiled for Windows and type-checked against the real API. It has not been run on a Windows machine yet. Two things specifically need a person and a real screen share:

• Whether WebView2’s transparent windows accept the flag at all. Jot’s windows are transparent, borderless and drawn by a web view. Display affinity has had restrictions on layered windows in the past. If Windows refuses, Jot logs it rather than showing an error - and the only way to know is to share a screen in Teams and look.
• Whether every capture path respects it. Most modern capture tools do. “Most” is not a claim worth making until someone has checked the ones people actually use.

Both are in the manual verification list with the rest of the meeting feature, and this post will get an update line when they have been walked.

Jot is a quick-capture app for Windows: one hotkey, one line, back to what you were doing. What it is, or what is still unproven.