We should consider removing this UI paradigm from our software. It's not supported on Wayland and on X11, most of our apps don't implement it at all or to a degree that's actually useful. Generally, out of the whole UI, only one or two buttons will have "What's This?" text, which is not a useful user experience; this is a feature that's really only useful if it's implemented truly universally, which it definitely is not.
See also D15307: Remove Context Help button by default. Let's figure out a path forward for removing this mostly-useless functionality. Instead, I think it would be better to focus on improving the the docbook documentation and the user interfaces themselves so they're as self-documenting as possible and have good tooltips.