OK, did some digging, but for any one else who is new to this stuff, I found that if you reference a style sheet (e.g. "MyEditorStyle.css") for the "EditWysiwygModeCss" property of the Editor control and then enter whatever background color you want for the "body" element (e.g. "background-color:Silver;"), it will color the full text area background in the editor for you.
Man I love Cute Editor! If only they'd change the name... How about "Extreme Editor!"