Sorry for the late response.

Both Internet Explorer's 'MSHTML editor' and mozilla's 'Midas' which is the component of the browser that makes it possible for products like Cute Editor to work don't support the creating of classes so we have to script that ourselves.

To get more predicatable behavior from our add class script we have piggybacked the change format abilities of these browsers so that it will add classess in the same predictable way that it changes the format.

The result of this is that it produces span tags when creating classes. The advantage of this is that the tags are properly nested and don't overlap helping us to produce valid HTML without needing to write lots of code.

We are also looking for a better solution to resolve this issue.