Change Custom Field display in page editor

In the WP page editor, I sometimes use a new Custom Field to put in some html or javascript into a page using a shortcode so that the visual editor doesn't muck things up... Works fine..

However, the Custom Field area is very small vertically, and if what you are placing there is larger than the box, you get a vertical scroll bar.

Is there a reasonably easy way to make the action of the Custom Field boxes rid of the scroll bar and instead expand vertically to encompass what you have put in the box?

Thanks!
Ken