How Can I Make A Sharepoint Textbox (input, Type=text) Dynamically Multiline?

I want a textbox on my Web Part that will grow vertically on demand. That is, it will be one line unless the user enters too much text for that line, at which point it word wraps a

Solution 1:

You're on the right track. You need to set the TextMode property to Multiline. However, the approach you took is to add an HTML tag attribute rather than set the .NET property. Simply replace boxPaymentExplanation.Style.Add("TextMode", "MultiLine"); with boxPaymentExplanation.TextMode = TextBoxMode.MultiLine;