// redball 

/ (no pixel graphics in k, so we fake it with a plot widget)

redball:{
 w.p::((0 16 16 0 0;0 0 16 16 0)+/:80&2 2_draw 100),0 1*\:2#,99 99	/ make squares
 w.m::{.[`p;0,x;y;1];if[~/2#w.p;`4:(`ok;`"game over")]}			/ move, signal end if red=black
 w[ `d`u`l`r]:"m .",/:5::'+(1 1 0 0;(-;+;-;+))				/ motion buttons
 w[~`d`u`l`r`p;`c]:`button`button`button`button`plot			/ classify objects
 w.[`c`a`l]:(`form;(`p;`u`d`l`r);`redball)				/ classify, arrange, label
 `show$`w
}