Safari compatibility (<strong> / <em> tags)

Similarly to what used to happen with TinyMCE (now solved, see issue here), also in HTMLbox under Safari (3.0) the Bold and Italics buttons give back this non-standard xhtml formatting:

<span style="font-weight: bold" class="Apple-style-span">This is bold text</span>

<span style="font-style: italic" class="Apple-style-span">and this is italic text</span>

instead of the valid strong and em.