Loading Piwik in IFrame using Safari

I have a problem with loading Piwik stats in an iframe using Safari 5.1.7.

On a webpage I have:

<iframe src="http://webstats.mydomain.com/index.php?module=Login

In Safari, the Piwik login page shows and you have to relogin, but if I open that link in new window it works. The site and webstats are on different domains.

The IFrame works in Chrome, Firefox and IE.

I’ve tried to add a header X-XSS-Protection with value 0, but that didnt do anything.

Is there some header I can add or something to make it work in Safari? I wouldnt like to have to tell customers that they need to edit options in Safari as a “quickfix”.

see How to - Analytics Platform - Matomo