In the minibuffer, the command accent-umlaut can be used to put an
umlaut on top of almost anything. (I.e. not only over the usual vowels,
but also umlaut over a numeral, over a [, and so on)
I consider this useful sometimes, such as when making little pictures
out of letters and symbols. Enhanched ascii-art. :-)
Sometimes, this generate invalid latex code though. This happens with
any kind of accent placed over the following symbols: { } _ ^ $ # % &
Not really surprising, as these have special meaning for latex. My
suggested fix is to escape them the same way as they are escaped when
they appear in the text, when they appear under an umlaut. That would
fix the error, and also allow accents over these symbols.
The ~ also have special meaning for latex, unbreakable space. Putting
an accent over the tilde gives a lonely accent, (accented ubreakable
space) instead of the accented tilde seen on screen. So this one should
be escaped also.
Attempting an umlaut over a backslash (accent-umlaut \) cause no trouble
with latex, but inserts the useless sequence \"{\} as-is into the
document text. The correct sequence is \"{\textbackslash} and it should
only be inserted at latex generation time, not into the document text on
screen.
