[Feature Request] Allow manipulation of HSV/alpha value

[astares]

Nice project. Maybe it can be extended to support not only RGB but also manipulation
of other values like

• HSV
• opacity / alpha value

like in other typical color pickers of graphic programs.

For instance this is the one from Paint.NET (https://www.getpaint.net)

or Gimp

https://www.youtube.com/watch?v=Y1PdMeTEQX4