Please, note that RadEditor uses the execCommand method
of the browser under which it operates to execute the Indent
commands. Each browser has its own implementation of these commands and they behave differently under the different browsers. IE wraps the whole paragraph in <blockquote
style="margin-right: 0px;" dir="ltr"> tags, but Firefox wraps the selected line in <blockquote>selection</blockquote> tags.
You can find more information about the execCommand method and its commands in the following MSDN and Mozilla articles:
Rich-Text Editing in Mozilla
If you would like I can tell you how to override the Indent and Outdent commands of RadEditor and you can try to implement your own custom commands.
the Telerik team