This idea is applicable to all windows and selectors throughout FileMaker where field names are not displayed in their entirety. Windows need to be able to resize to display all content or tool tips added to display the full field name. I've have a particular issue with the following scenario:
Adding a new report layout, when 'organizing records by category' the report field picker cannot be resized and no tool tip available to display the field names in full. It's fine if all your field names are less than 16 characters in length otherwise it's extremely frustrating especially if you're working with fields from related tables.