The Symbol dialog enables end-users to visually select a symbol or character insert it into the text.
End-users can invoke this dialog using the Symbol button on the Insert ribbon tab. Refer to the How to: Create the RichEditControl with a Ribbon UI topic on how to provide the ribbon ui for the RichEditControl. Executing the ShowSymbolFormCommand invokes this dialog as well.
RichEditControl also provides a number of commands to insert different individual symbols:
Handle the RichEditControl.SymbolFormShowing event to customize the default Symbol dialog or substitute it with completely new one. To get an example of the dialog replacement, refer to the How to: Customize the Search Form or How to: Customize the Hyperlink Form document.