Snapping to guide lines while cropping in the viewer

Hi, I'm looking for a certain feature in FCPX that I've been using in ScreenFlow.

I know how to crop the frame of a clip to reduce the visible area in the viewer.

In my project I need to work with a screen into 3 parts in multiple videos.

Is there a way to activate snapping to guidelines for the cropping so that I can easily crop to my 3 standard dimensions?
The viewable part of a certain clip may differ so that I can't just copy the settings.

Thanks a lot!

Snap to the viewer's center is about the only snap-to there is. This actually sounds like a job for a custom Motion template, if you have the 3 parts in a standard configuration all the time.

You can try this free grid ... no snap but very usefull.

www.digital-heaven.co.uk/dh_gridx