Curves histogram to reflect masked area of image

Currently the histogram in the curves tool reflects RGB/luminosity values for the entire image. However, it would advantageous to have the option for the curves histogram to reflect only the masked area of the image so that one could make specific, detailed changes to the masked area using the curve tool. Other software provides this function (Affinity Photo, Lightroom, Photoshop) but at this time, Capture One doesn't. I find this particularly useful for black and white images and adjusting localized contrast.