After stabilization video window is wiggling at the sides

Yosemite 10.10.3, FCPX 10.2

I have never worked with FCPX before, actually also not with OSX as I had a PC before.

I have applied stabilization to one of my old digitized Super 8 movies. Impressive what the software does. But the disturbing side effect is that the video window now constantly moves back and forth to the sides. Is there a way to avoid that, something like an automatic crop?

Thanks.

Kraut55