Add input type color

[mvorisek]

ref: https://www.w3schools.com/tags/att_input_type_color.asp

[PhilippGrashoff]

Just found this, I am using this since 2018. Really simple, can add a PR if wanted.

use Atk4\Ui\Form\Control\Input;

class Color extends Input
{
    public string $inputType = 'color';
}

[mvorisek]

There is https://github.com/atk4/ui/commits/add_color_control branch already. IIRC I wanted to normalize the color and style it a little better, as color wide as regular input is probably not much helpful.