Displaying webarchive in HTMLViewer in Mojave

When I load a local .webarchive file into an HTMLViewer I’m getting only a blank page. I swear this used to work, which make me suspect it may be a Mojave security issue. I’ve included Allow Arbitrary Loads in my info.plist. Is there some other setting I need (note this is not a sandboxed app)

Isn’t .webarchive files the native Safari stuff ? Yes, it is.

Get the url for that page and load / save with Firefor / Opera / whatever…

Edit:
Mojave have nothing to do in that.

Actually, these are webarchives saved from a Xojo HTMLViewer.

And HTMLViewer us the same technology Apple used to create/build Safari.

Safari allows to Export as html source, will HTMLViewer able to do the same ?

HTMLViewer (from LR):

Renders HTML and provides basic navigation features.

So this is not a Web Browser.

Same advice:

I know what an HTMLViewer is, I’ve been using them for years. And in the past they displayed webarchives saved from itself (via declares) and from Safari. I was just able to test on a system running 10.12.6 and antheHTMLViewer indeed displayed a webarchive saved from Safari. The same webarchive isn’t displayed by the same project in Mojave (it loads but appears as a white background – right clicking on it just gives you the opportunity to Reload). So it certainly smells like a security problem to me. I’m hoping it can be resolved with a setting in info.plist, but so far I haven’t run across anything that works.

Same 10.12.6 here and a .webArchive appears blank if I try to display it in Firefox.

Nota: I use HTMLViewer to display help in a project and HTMLViewer to view pages in an application created just to do that. None of them save anything to disk. Not intended to do that, I use a Web Browser for saving (and printing to pdf).

Edit:
Incredible, my Help based HTMLViewer knows and displey .WebArchives files !

Please see my last post. Xojo 2019R1.1 HTMLViewer displays a Safari-saved webarchive in Sierra, not in Mojave. So of course the HTMLView can display a webarchive – but it’s not in Mojave, so unless someone proves otherwise it’s a security issue. Perhaps someone else has suggestions for resolving this.