It is very easy to insert an HTML element in an existing text. For example, suppose that in some text there is the word "important" which you want in boldface. First select the word.
Then choose "Bold" from the menu (or type the equivalent key binding) and "important" will be wrapped by the HTML tags to give
<B>important</B>
This behavior is the same for all elements which are containers. Inserting an HTML element never deletes a selection.
