This is a tiny addition so i'll keep it short and sweet.
For making a 1 primary color site it would be great to really quickly bump up or down a shade when creating elements.
It would help with creating palettes on the go rather than having to pre-make them or drag around the color sliders inaccurately.
see material designs shade swatches for ideas on how big each shade difference should be. https://material.io/guidelines/style/color.html#color-color-palette
(as a sub idea, arrow buttons on the top and bottom of the transparency and HS*L* slider would also have the same effect (hold shift to bump by 10%))