Telerik version 2011.1.614.35
I am facing following two issues with RadEditor on Chrome (version 28.0.1500.95) and Safari (version 5.1.7) -

a. Gray area is seen in the lower part of the RadEditor for Design and Preview modes. When some text is typed, the gray background vanishes for that line of text. 

b. Border of the RadEditor is not complete at the bottom left corner in the HTML mode. This behavior is seen whenever there is some text in it, be it the default text or the text of the field that is bound. 

Please refer the attachment RadEditorIssues.png