m = peripheral.wrap("top")--find monitor peripheral
xSize, ySize = m.getSize()--get size of the monitor
xMin= (xSize/2)-4--the leftmost point of each button
xMax = xMin + 10
spawners = {["zombie"] = false, ["wither"] = false, ["blaze"] = false}--store the states of each spawner
buttons = 3--number of buttons there are
joe = false--whether or not killer joe is on

button.clearTable()
button.setTable("Zombie", function() derp end, "Zombie", xMin, xMax, ySize/buttons, ySize/buttons)
button.screen()