On recent versions of macOS, when a window is being shared (via the system screen-capture APIs), the OS sometimes shows a small "shared window" badge in the title bar.
I’ve noticed that this indicator is not consistent:
- For some windows, the badge reliably appears when they are being shared.
- For other windows, the badge never appears, even though the window is actively shared.
In particular, windows that use a standard system title bar seem to show the indicator more often, while windows with custom-drawn or non-standard chrome do not.
My questions are:
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What are the exact conditions under which macOS decides to draw the “shared window” indicator in a window’s title bar?
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Is this strictly tied to certain NSWindow styles or masks (e.g. titled vs borderless)?
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Is there any API or flag I can use to detect programmatically whether a given window will display this system indicator when shared?