@Simeon @John - the current colour selector is great at quickly picking a colour, including alpha, in run mode. Even displays the r,g,b,a values. But, if you want to put precise colours in place that is difficult to manipulate. All I am suggesting is you convert the colour r,g,b,a vales displayed to selectable fields so you could place exact values in them.
https://codea.io/talk/discussion/10653/color-changer-glsl-chroma-key
has a nice color selector with sliders-but you will have to replace all the table.maxn with #
@Marcelino @piinthesky - thanks for pointing that out, I remember it from when you first posted it. At the time seemed like a better way of displaying/selecting colours. Remembered it well - since the code was in an older Lua version which deprecated table.maxn() but a simple one liner resolved that. Would be nice if the colour circle plus alpha slider was the default with a selector option to expand and include the colour sliders or switch between utility screens.
table.maxn = table.maxn or function(t) return #t end
Use that line in global scope above Function setup().