It'd be really good if the eyedropper could be constrained to picking from a particular DOM element.
This would useful where that element contains a subset of colors that are legal. We have a specific case where we want to let the user pick a color from a video frame to act as a key for that frame - it doesn't make sense to allow them to select a color from outside the video element.
Here is some feedback from @jamespearce2006 following the W3C/SMPTE joint workshop, originally received on this issue: https://github.com/w3c/media-production-workshop/issues/36