Hi, this description is from the closed ticket #8927, but as I have exactly the same issue, I felt that I could just copy/paste it here... Contrarily to the other developer though, I have a working example in production:
The calendar on the homepage loads a fragment from another page to get the current month's events. If I remove the load call, the mixed content warning isn't displayed anymore.
This affects only IE7 and IE8. Other browsers tested such as FF 4, Chrome 12 (dev), IE9 (on Windows 7) were unaffected.
According to the other ticket, if there are two pages, Foo.html and Bar.html, both on the same domain and both using https, the .load() function operates correctly and without any mixed content warning if loading the entirety of Bar into Foo.
However, if a fragment of the target page is being loaded, a mixed security warning is generated.
URls for reference:
Example (in Foo.html) $('#content').load(' https://www.mydomain.com/production/Bar.html');
However, if loading a fragment from Bar.html, IE7 and IE8 throw the mixed security warning.
Example (in Foo.html) $('#content').load(' https://www.mydomain.com/staging/Bar.html #fragmentToLoad');