UFO Appearing on Video Viewer

Hello- (SEE: attached screen shot)

I have this rectangular box with a movable red box within it that has appeared within my video frames within the video viewer. If you click and drag the red box it moves the subject matter from left & right positions (gives you a little horizontal movement to center I guess).

I have never seen this until updating to FCPX 10.2.3. I don't know if I inadvertently turned it on or not, and don't know if it will remain embedded in my video unless removed.

Anyone know about this? How do you remove it?

TIA,
Robes

It has always been there. It appears when you zoom in on your video frame. Click in the Viewer to make it the active pane. Use Shift-Z (fit to window), and it will go away. Use Cmd+ to zoom in, you'll see it reappear. Zoom in more, you'll see the red area (the area of the frame you're currently zoomed in on) get smaller, the more you zoom in.

...and I thought it was some two dimensional alien, I see how it works now -

Thanks Again