I've successfully created and registered a custom protocol handler in my web application and it's working fine in all browsers. There's the initial warning dialog about launching an external application which is fine.
However when the app is deployed and the site is running under SSL, the custom protocol links no longer work in Chrome. I see the following message appears in the Developer Tools console:
[blocked] The page at https://my.site.com/path/to/page ran insecure content from iwd:-action=myaction
The same links work fine in Internet Explorer and Firefox.
Any ideas as to how to make this work? My external application by the way is a console application that's installed on the client.
edit: One extra important piece of information is that the link specifies a target which is a hidden iframe on the same page.