Pinnable task pane behavior is't consistent between Outlook client platforms

[Luspin]

Article URL
Implement a pinnable task pane in an Outlook add-in - Office Add-ins | Microsoft Learn

Describe the problem

• In all other platforms, an add-in's task pane will only remain open if the end user pins it, and it will be automatically dismissed once the user selects another message.
• However, in Outlook for Mac, an add-in's task pane always stays open, whether or not the end user pins it, and it will trigger the SelectedItemsChanged event.
• If the add-in is pinned by the end user, then it will also trigger an ItemChanged event i.e. it triggers both ItemChanged and SelectedItemsChanged, which is in accordance with the documentation.
• This persistent task pane behavior is only seen in Outlook for Mac clients.

Screenshots
Provided in [Update pinnable-taskpane.md · PR #5274 · OfficeDev/office-js-docs-pr]

[samantharamon]

Hi @Luspin,

Thanks for creating this issue. As discussed in the PR, the task pane behavior you reported for Outlook on Mac also applies to Outlook on the web and new Outlook on Windows, i.e., the task pane remains open even if it hasn't been pinned by the user. However, if you're observing different behavior in Outlook on the web and new Outlook on Windows, please let us know and we'll be happy to look into it.