I'm using wp-latex and/or wp-quicklatex to set math formulas; latex uses backslashes to denote its commands. I'm also using FEE 1.5.1. In its given form, FEE strips the backslashes at second edit -- that is, I can create a formula and it will display, but if I edit it with FEE, I find that the backslashes are stripped.
The relevant code is in core.php, lines 194-6:
$content = stripslashes_deep($_POST['content']);
$result = $instance->save($id, $content);
$result = @apply_filters($name, $result);
The LaTeX packages work with the change of these lines to
$content = $_POST['content'];
$result = $instance->save($id, $content);
$result = @apply_filters($name, stripslashes_deep($result));
That is, stripslashes is applied not to what is saved but only to what is returned, so we avoid recursive stripslashing.
I think that this is the right way to do it (regardless of the use of LaTeX) -- stripslashes should be applied to the data as it is used, not as it is saved.
@scribu: Does this seem to you an acceptable/appropriate change?