Well, I know I sound arrogant, but what have YOU learned.
I don’t mean to be, but running anything in a frame or iframe is not a good way to do things.
Frames are antiques, things hated while they were popular and therefore not done much any more unless absolutely necessary. Iframes are abused by novice designers who try to run their posts in them. Search engines don’t “see” what is in an iframe, and they have lots of other problems…so they are used for ads and other non-essential purposes.
There are over 300 different themes to choose from, and some have incredible designs. If you are determined to run your WordPress from within a frame or iframe, then you have to live within those limits and understand them. If you are trying to do something else, like run WordPress from within a static html page or a non-WordPress page or site, then we can help you with that issue.
For now, you’ve learned that to log in, open a new window for your login.
I use Firefox as my browser and I have multiple windows open all the time in “tabs”. I always have one page open for my WordPress Admin, another for my site, and then the rest for whatever I’m working on. It’s not a big deal to do.
I hope this helps, a little. We’re trying to give you the best help we can, but doing the odd and unusual makes it a little more challenging.