[BitBucket user: Sébastien Jodogne]
[BitBucket date: 2019-01-20.09:02:45]

This is not a built-in feature of HTML5. It can only be implemented on a per-browser basis (check out https://stackoverflow.com/a/49745626/881731). Check out our FAQ related to Orthanc Explorer: http://book.orthanc-server.com/faq/improving-interface.html

Feel free to implement an Orthanc plugin that implements this behavior by yourself: http://book.orthanc-server.com/developers/creating-plugins.html

Alternatively, you could try and find funding for this development.