Clip warning should be an easy-to-access toggle
Currently, getting clip warning to display means one has to manually enable and configure the Clip Warning display filter per every image.
Re-implementing it as a per-image toggle easily accessible via menu and keyboard shortcut (with global options in the Preferences dialog) would significantly improve usability of this very useful feature.
My suggestion would be View -> Color Management > Clip Warning for menu and Edit -> Preferences -> Color Management (with new Clip Warning group).
We also might want thinking of using the right part of the status bar for toggles: clip warning, color proofing, showing grid and guides. But that's probably a topic for a separate feature request :)