Hi,
The TextBox control does not supports multiple fonts, or font sizes in one sigle box. Some controls like the list control accepts escape codes, that allow you to have fonts with different colors.
The best option that I can think of is to use an ActiveX control. probably you can use a web brwoser to display multiple font sizes and styles. You would save the text to a simple html file that you load in an embeded web browser.
You can find some examples for the list control and the ActiveX web browser in CVI's shippong examples.
I hope this helps, please let me know if you have any further questions.
Regards,
Juan Carlos
N.I.