on.keychord_press = function(chord, key)
	if chord == 'C-n' then
		animate(new)
	elseif chord == '`' then
		if Draw == 'problem' then
			Draw = 'solution'
		elseif Draw == 'solution' then
			Draw = 'problem'
		end
	elseif chord:match('%d') then
		-- cursor visible
		local x,y = Cursor[1], Cursor[2]
		if x > 0 and y > 0 then
			-- it's not in the provided square
			if x ~= Problem.x or y ~= Problem.y then
				local c = Problem.data[y][x]
				local d = (string.byte(chord) - 48)
				if c == '' then c = 0 end
				if c < 2 then  -- not overfull
					Problem.data[y][x] = c*10 + d
				end
			end
		end
	elseif chord == 'backspace' then
		-- cursor visible
		local x,y = Cursor[1], Cursor[2]
		if x > 0 and y > 0 then
			-- it's not in the provided square
			if x ~= Problem.x or y ~= Problem.y then
				local c = Problem.data[y][x]
				if c ~= '' then
					Problem.data[y][x] = math.floor(c/10)
					if Problem.data[y][x] == 0 then
						Problem.data[y][x] = ''
					end
				end
			end
		end
	end
end