Under MacOS X 10.7.x, when the Font Size of Chinese/Japanese equal to 13(FontFamily="Arial" FontSize="13"), the words are blurring under most of controls, such as RadRibbonBarăTextBlock and RichTextBox. But it is clear under MacOS 10.6.x. There is a Demo under URL: http://demos.telerik.com/silverlight/#RichTextBox/TelerikEditor, when the font size is 9, the display is in disorder.