We are using the Kentico 9 Document Library Widget to display a list of files in a folder. But what I cannot find is a way to set the sort order of the files being displayed seems to be random.
Do I have to customize the widget to have to do a sort based on a date field for example?
You have to make ORDER BY property visible in Widgets application. You can set default value or set proper ordering in widget properties dialog.
Note to Boris: Document libary is one of the abandoned features in v9.