Add Header property to TextBox control
Even the "TextBox Control Design Guidelines for Windows Phone" (http://msdn.microsoft.com/en-us/library/hh202916%28v=vs.92%29.aspx) says that a TextBox must have a Header such property isn't supported by the TextBox control. Even the "Windows Phone 7 Toolkit for Silverlight" contains some improved controls using Header property the TextBox control was forgotten? See also: http://forums.create.msdn.com/forums/p/76127/576970.aspx
@Harald-René Flasch, can you share your code?
PS: it's very strange TextBox doesn't contain one. Shame MS!