Onion Skin Range Trouble

Hi, good day. I start to use synfig 1.3.12 for the first time I have to use Onion Skin option in one of my new works, but I noticed that there are no range options for the onion skin, I try to search in the menus but I cant find it. Is the option simply hidden or has it been completely removed?

You mean the top-right corner of workarea (above horizontal ruler), left to (red) stop button?

Hi, good day, thanks for the time to respond.
Oh I see, I try it, but Still have a little problem with that…

it seems that the new Preview button cover a lot of space, the same with the onion skin range options, Maybe reducing the width of the Onion Skin ranges BOX in 20 pixels every box, because in this moments looks like you can put like 9999


I don’t think that we will need all that space for Onion Skin Range in that boxes or maybe changed for something a little more tiny like this with onion skin for previous frames and another for later frames and could be activated and deactivated by clicking on the Bouncing Balls

image (I made this using gimp)
Or something more more basic

I would do it myself but I dont know noting about Python or Programing