Stimulus List -- No "Add File" or "Add Folder" button

I am trying to create File Lists. I Selected Stimulus Lists. The Stimulus List Editor appeared and I entered a name for the list, set the type to File, and indicated that files are for use with Picture Files. There was no “Add Files” or “Add Folder” button on this screen. There is no place for me to indicate which file/folder I want SuperLab to use.

In some cases, it’s possible for the window to be smaller than the intended minimum. Click and drag the lower right-hand corner of the window to make it bigger, and the buttons should appear.