Underline position and thickness

I have a input box where can apply underline for the selected text.When underline is applied using textformat the line is coming just near to text.If any descendent letters like ‘g’,‘q’,‘p’,‘j’ or ‘y’ is present in text box then the underline is cutting off. So I want to know is there any method available in AS2.0 to control the underline x and y position and also to set the thickness of the line.