OneNote Interop API targets wrong window instance when multiple

Question

C# with .NET Framework 4.8, Microsoft® OneNote® 2021 MSO (Version 2410 Build 16.0.18129.20100) 64-bit

Open up two OneNote windows viewing the same page. From the second window, invoke an add-in command that uses the managed Interop API.

Any queries or updates made by the API will target the first OneNote window instance, even while the second window instance is active and has focus.

However, if the content of the page is manually modified from the second [active] window instance, then and only then will the API call target and update the page in the second window.

Expectation is that the updated page content will be visible immediately in the active OneNote window instance.

Answer 1

A great example of this is when your add-in wants to know "what is the selected text" in the focused, second instance, as the XML request will always give the results from the 1st instance. If you close the first instance or move to another page in the 1st instance, the query will give the correct information.