When using the Safari browser included in Mac OS X, the execution of a spell check operation will mingle certain characters in the source of the page, causing all lists to be broken upon the next "Preview" or "Save" operation.
We experience this behavior with DokuWiki running on both a Linux server and a Mac OS X server. I did a capture of the traffic between the Safari and the server (included as file "safari" in the attachment). For reference, I also captured traffic between Camino (=a browser that does not exhibit this behavior) and the same server.
Jugding from the diff between these two captures, things go different when the browser calls the "resume" function of the spellchecker to convert the text from HTML back to plain text. Camino's HTML starts each item line as such: (in URL-encoded form)
%26nbsp%3B%20*%20Item
Whereas Safari has:
%C2%A0%20*%20Item
So Camino has " " where Safari uses "\xC2\xA0" (the latter is the UTF8 encoded form of U+00A0 or NO-BREAK SPACE).
I don't know whether this output is allowed or caused by bug in either Safari or the JavaScript part of DokuWiki, but given this information, my quick fix was to add the following to the conversion code in the spellcheck resume function (see patch in attachment):
$text = preg_replace('/\xC2\xA0/',' ',$text);
This solves the problem for me.