Demo file: scrolling-the-unscrollable-v2.zip
Howard Schlossberg’s presentation on popovers (FileMaker 13 Popovers) has inspired me on multiple occasions… a favorite takeaway is the idea that you can have a scrolling check box set within a popover.
The trick is to size the field as tall as necessary to display all the values (this is an extreme proof of concept with several hundred entries), but the popover itself can be whatever height you wish.
Note that initially you will need to size the popover tall enough to encompass the field containing the check boxes… then, once the field is properly sized within the popover, you can change the height of the popover. Just don’t move the field once you’ve done so.
And here it is in browse mode.
Thank you also to Rob Russell for pointing out that a. you can scroll other “unscrollable” fields, such as static containers, and b. that they can be scrolled both horizontally and vertically.