BlueGriffion by Disruptive Innovations is an open-source Mozilla powered web page editor. I used this a little bit the other day. It does seems like it can do quite a bit and a lot more stable than the NVU web authoring software which is the predecessor to BlueGriffion. Of course most of my sites I have converted over to WordPress so I don’t really use a desktop web page editor much any more.
” BlueGriffon brings support for the most modern web technologies including HTML5 new layout, form and media tags, ARIA, CSS3, SVG features including transitions, transformations, shadows, and a very long etc. “