Help! I want to take a scan, but I have only one scan type to choose from in the scan menu!

Plus, I can't adjust the field size of the scan either!

You have marked a rectangle on the currently opened scan. In this case, SM_GUI assumes you want to scan exactly the area of the scan (which must be the same scan type, of course).

Cancel the scan setup, click the left mouse button once into the image window to get rid of the rectangle and start over.