Finally I've started fixing the most annoying bug in Write Area, the lack of tooltips, and thanks to this post by Zoolcar9 I've been able to fix the problem by using a xul file that embeds the html page instead of showing it directly.
It has lead to other code changes so now I have to review that everything keeps working.
Meanwhile I've added a save/load pair of buttons, so you can save your drafts on your computer. I've to review here that the encoding of the files is done properly as the docs state that it isn't utf safe by default.
For the moment it's saving just the content of the <body>, but I guess that I'll create some full html files just in case anyone wants to doubleclick them.
(for the new icons I've picked the load/save file in the Crystal pack by Emeraldo, but if anyone else has a good suggestion just drop a note here)