Overlaid mill files with gerber

[CreativeSoftware]

When it is rendered a mill file in all gerber readers appears “crosses”. The machine “knows” when it hits a cross it stops the drill at this point and jumps after the cross continuing the work on the FR4. On the pcb it creates a “bridge” which is later broken at the end of the fabrication process.
For visualization purposes makes sense when it is overlayed a mill with a copper layer create a bridge instead of the cross, it is closer to real world visualization.