I've got a Word add-in working well on Windows, and the basics are working on Mac also (Word 2016 both).
What browser does Word 2016 for Mac use? I see this post: What browser / browser engine do Office Add-ins use?
But it doesn't explicitly define the way Mac does it.
I see posts about clearing the cache, which is helpful (that will be my next challenge) like How to clear client side browser cache for Excel 2016 Task Pane add-in on Mac?.
Specific reason I'm asking is trying to use Firebase for authentication. On Windows, because Word 2016 uses IE11, clicking Login (with Firebase running the show) in my taskpane pops open IE11...and the login through the full browser is recognized by the Taskpane.
On Mac, clicking Login is opening my default browser...
Alternately I could try to keep the Firebase flow in the Taskpane...but not sure how to do that:)
Mostly curious how Microsoft is kludging this on Mac.
For Mac, the native WebKit control is being used (https://developer.apple.com/reference/webkit/webview). Window.open or other popups will open in the default browser and not share cookies or have window.opener pointer to the WebKit control by default. This does not work in authentication scenarios. If you want the popup window to be opened in a separate WebKit control for authentication, you will need to include the trusted domain in the AppDomain list of the manifest: https://dev.office.com/reference/add-ins/manifest/appdomains. window.opener and cookies should then work between the popup and add-in. The AppDomain list is supported on every platform.