* `on.mouse_move(x,y, dx,dy, istouch)` -- called when you move the mouse.
  Provides in `x` and `y` the point on the screen at which the click occurred
  and in `dx` and `dy` the amount moved since the previous call of
  `mouse_move`.
  (Based on [LÖVE](https://love2d.org/wiki/love.mousemoved).)

end
function App.mousemoved(x,y, dx,dy, istouch)
  if on.mouse_move then on.mouse_move(x,y, dx,dy, istouch) end

  --   on.mouse_move (see love.mousemoved)