there are two options to alter the output.
A slider can set the opacity of the colour between
fully transparent and opaque, representing it with a value between 0 and 1.
Clicking on the Flood Color it brings up
a color picker panel, with multiple inputs.
Hex color names and RGB values are of the same
as in the fill and stroke panel, however the HSL wheel
is not 0-255 based: hue has a 0-360 scale,
while the saturation and lightness can be set
between 0-100 values.
An important feature is that there is also a dropper tool
included with the panel which can take
any part of the screen as a reference.
Let's change the default black to red.