Thanks for the pointers. Yes, I know the MouseText characters are present in Unicode, but it doesn't describe how they were intended to be used, it just provides them for compatibility.
For example, the screenshot in the 1985 Apple II HIG shows something like the character at 5E (in the table on Wikipedia) being used for the close box at the upper-left... but is that intended? The character at 5E doesn't have a left-hand edge, and I'm guessing that it's supposed to be used next to the character at 5A to provide that left-hand edge, but that's just my guess. I'd like to find some more reliable source.
For example, the screenshot in the 1985 Apple II HIG shows something like the character at 5E (in the table on Wikipedia) being used for the close box at the upper-left... but is that intended? The character at 5E doesn't have a left-hand edge, and I'm guessing that it's supposed to be used next to the character at 5A to provide that left-hand edge, but that's just my guess. I'd like to find some more reliable source.