draw_ticks = function()
	if App.fake_key_press then return end  -- disable in tests
	local old_font = love.graphics.getFont()
	love.graphics.setFont(Ticks_font)
	love.graphics.setColor(0.6,0.6,0.6)
	-- x axis
	local anchorlo, anchorhi, scale = tick_spec(Viewport.x, Viewport.x+iscale(App.screen.width))
--	print('x ticks', Viewport.x, App.screen.width, iscale(App.screen.width), anchorlo, anchorhi, scale)
	for x=anchorlo,anchorhi,scale do
		local vx = vx(x)
		love.graphics.line(vx, Menu_bar_height, vx, Menu_bar_height+5)
		love.graphics.print(('%2.0f'):format(x), vx+2, Menu_bar_height+5)
		love.graphics.line(vx, App.screen.height, vx, App.screen.height-5)
		love.graphics.print(('%2.0f'):format(x), vx+2, App.screen.height-15)
	end
	-- y axis
	local anchorlo, anchorhi, scale = tick_spec(Viewport.y, Viewport.y+iscale(App.screen.height))
--	print('y ticks', Viewport.y, App.screen.height, iscale(App.screen.height), anchorlo, anchorhi, scale)
	for y=anchorlo,anchorhi,scale do
		local vy = vy(y)
		love.graphics.line(0, vy, 5, vy)
		love.graphics.print(('%2.0f'):format(y), 5, vy+2)
		love.graphics.line(App.screen.width, vy, App.screen.width-5, vy)
		love.graphics.print(('%2.0f'):format(y), App.screen.width-40, vy+2)
	end
	love.graphics.setFont(old_font)
end