How to have tag panel item refer to other tag

I'm trying to get a value in the Tag Panel to refer to another tag. Specifically, I'd like to have "Album Artist" refer to/copy/enter the "Artist" tag.

Basically (but not always) I'd like to have a way to have the Album Artist field refer to whatever is in the Artist field. Yes, I could do it in another way (If there is another way that would be easier than this way, tell me where to go) I suppose, but this seems to be the easiest, especially when I load multiple different artists (like a compilation album).

I'm not looking for the answer, but if anyone can point me in the right direction, I'll try to figure out the rest. I've tried "%artist%" but that didn't work.

Any advice?

I am not quite sure what you mean by

There is a "Howto" about copying 1 field to another - which I think, is the only way to do it properly:

You cannot use the Tag Panel to have one field get data from another.

I suggest you create an Action that can be called any time you wish. I that Action you can then use Format Value for ALBUMARTIST, and use %artist% as the value.