highlight clipping

Thank you. 

If you want to know exactly which image pixels are clipping in each channel, you can do it the same way as in Photoshop: Hold down the Option key (Alt key in Windows) while dragging any slider that can clip. This causes the on-image overlay to display the colors Rikk listed, to indicate which channel(s) are clipping.

Don't you already?

The Highlight Clipping triangle changes colors according to the channel being clipped, 

Red
Yellow (if Red and Green)
Green

Cyan (if Green and Blue)
Blue
Magenta (if Blue and Red)
White if all three channels

Or are you looking for something different?