RichTextBox.SelectAll Method
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Selects the entire contents in the RichTextBox.
Assembly: System.Windows (in System.Windows.dll)
The selection highlight is invisible if the RichTextBox does not have focus. So, if you want to implement a "Select All" button in a toolbar it is good practice to call RichTextBox.Focus after SelectAll.
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