Custom Controls - Control Settings input field height/styling - or perhaps specifying as a Text area?

Hi there

I have a Custom Nintex Form control that is working fine.

However, some of the properties of the control that are set as 'strings' in the .NET code need to hold a fair bit of text (more than one line's worth of text). However, in the Nintex form designer, when configuring the 'Control Settings' for these properties on the custom control, the input fields are just normal HTML text boxes. When there is a lot of text, they get tiny little up and down arrows to scroll through the text.

Is there anyway to solve this by eg: 

1. Specifying a <textarea> field to be used for the Custom Control property
2. Giving the <input> box a height somehow (eg. configuring an inline CSS property for the Control Settings field)
3. Specifying a CSS file (to style the whole 'Control Settings' dialog)?

Any input greatly appreciated.

Cheers
Matt