First, congratulations for the product works really well, but I found some anomalies in Firefox (version 3.6.9) and Opera (version 10.62).
The problem is related to DropDown elements and RenderRichDropDown property.
Firefox
RenderRichDropDown = true - items are displayed outside the editor box (but work)
RenderRichDropDown = false - items are displayed correctly (but don't working)
On firefox there's another problem: when you click the second time a dropdown box, items remain visible
Opera
RenderRichDropDown = true - Css Class, Inline Style, Font Name and Font Size don't working - Paragraph, Links, Code Snippets and Images work
RenderRichDropDown = false - entire editor hangs
On Chrome (version 6.0.472.55), Safari (version 5.0.2), IE 6 SP3 and IE 8 all works correctly
Best regards
Roberto Gallicet