Lightroom's "Show selected mask overlay" option for the Adjustment Brush is an excellent capability and I use it very often. I see there are four (4) different "color" choices for the mask overlay and, so far, using the (red and green) colors other than black and white have been most beneficial to me. However, my brother who also uses Lightroom is not able to reap the same benefit because he is red/green color-blind. If the color-picker (or a wider range of colors) could be used to choose the color of the mask overlay it would benefit all our color-blind peers. Thank you for considering this for mask overlays and any other place it makes sense! If you need more input for this request from me or my 2 color-blind brothers, please don't hesitate to email me.