MT https suckiness

This event has been the first time, where i have been written some more blog entries over an insecure network since the MT4 upgrade. So this is the first time i noticed this problem with my blogsoftware.
I have been using https for the blog for some time. Unfortunately the new MT4 JavaScript^WAJAX navigation seems not to work if i access the admin frontend via https. I tried both Safari and Firefox.
If i rerequest the form with http everything works. I have no idea why.