Maybe you have noticed when you move or scale a source in the preview window that the snap feature does not allow you to precisely position your window near an edge because it will snap to the edge.
Instead of snapping, OS X implements edge resistance instead. Meaning when you move a window against the edge it will stop moving for a few pixels of mouse-movement, then once you move further, the window starts moving again (without jumping). This allows for precise movement of the window near an edge but still very easy to place the window exactly on the edge.
I think edge resistance could be useful for source placement, scaling and cropping.
Instead of snapping, OS X implements edge resistance instead. Meaning when you move a window against the edge it will stop moving for a few pixels of mouse-movement, then once you move further, the window starts moving again (without jumping). This allows for precise movement of the window near an edge but still very easy to place the window exactly on the edge.
I think edge resistance could be useful for source placement, scaling and cropping.