#include "color selection.dms"
mob
verb/choose_color(c as color)
winset(src, "button", "background-color=[c]")
// color selection.dms: (it's just a button)
<body>
<div id=button byondclass=button skinparams="text=Color; command=choose-color"></div>
</body>
result
I assume it's supposed to show some kind of gradient in those black rectangles. :(