it should to return xaml content. The contents are always blocks. Typically, these are Paragraph elements
However, u can use vector light rich textbox. http://www.vectorlight.net/controls/rich_textbox.aspx. It supports plain text.
Donot know if it is the best way, but since its workng..cheers
Sharker Khaleed Mahmud
You can also get the value using TextRange class.
See the sample code in the link below.