controlling width in UITheme class >> exampleBasicControls

UITheme class >> exampleBasicControls generates 3 columns.  I want to
control the width of the text entry input area ("Hello") in the left most column

In the example, the width depends on the width of the widest text label
in that column. If there are no labels, the text input box shrinks to a
useless width (about 3-4 typed characters).

How can I set the width of the text input field?