One option would be to use the bound value of the dropdown. Select the dropdown and in the Object > Field palette type in the Display Value for each item on the list. This would be a short description to suit the width of the dropdown. Then in the Object > Binding palette, tick Specify Values. You can then input in your long description as the Bound Value for each item.
Lastly set the Binding to Global and drag on a TextField with the same name as the dropdown.
While the dropdown will display the Display Value, the textfield will display the .rawValue/Bound Value of the dropdown.