How to stop a sliced image from shrinking with the container?

Hello. I'm having a bit of a hard time figuring out how to stop an sliced image, with borders set on the sprite editor, to stop from shrinking when the container's size reaches the sprite's borders. I thought the border would be enough, but it doesn't work the same with shrinking as it does with expanding.

So, I have this image: http://prnt.sc/f49vml

After I shrink the container (it's a button, btw): http://prnt.sc/f49vy4

How I would like it to be (the part within the rectangle): http://prnt.sc/f49wgb

As i said, I hoped the image would get cut, sort of, after the container reached the sprite's border. But that doesn't seem to be the case.

Thanks.