Browser widget: "Navigation request cancelled"

[Ben Rubinstein]

Trying to use the browser widget to access an internal site, I'm having a lot 
of trouble.

If I send it (by setting the URL property of the widget) to the root of the 
hostname, it loads the page succesfully, although the widget gets a 
browserDocumentLoadFailed message "navigation request cancelled".

If I set the URL property to some pages within the site, they load succesfully 
without that message.

If I set the URL property to some other pages, they do not load, and that 
message is received.

It's completely consistent which URLs work, and which don't.

If I send the widget to a URL which works, I can navigate anywhere within the 
site without problems, including to the URLs which don't work using set.

I haven't managed to pin down what distinguishes the working URLs from 
non-working. All the non-working ones I've found involve query parameters; but 
some of the working ones do also.

My question is: how can I debug this issue? Are there any ways to get insight 
into the loading process?

I am catching and reporting these messages:
	browserDocumentLoadFailed
	browserDocumentLoadComplete
	browserNavigateFailed
	browserNavigateComplete
	browserUnhandledLoadRequest

... but the only ones that trigger are either browserDocumentLoadFailed or 
browserUnhandledLoadRequest, or browserDocumentLoadComplete - always with the 
parameter being the requested URL. I'm guessing, though I might be wrong, that 
the issue is actually with one of the elements being requested by the 
document, but this is never in the parameter.

Additionally, browserProgressChanged never seems to be sent.

Is it possible to get any more detail about what's going on?

TIA,

Ben