How to flip (mirror) the whole design from top to bottom (parts, traces, vias)?

One way is to create a Place Replica of the components, clines, vias and shapes while in Placement Edit App Mode.  Once the replica is created the objects will be part of a group which can be moved or mirrored together by enabling GROUPS from the Find Filter.  Once the mirror is completed you can disband the group by selecting it and using the RMB > Disband Group.

Creating a Place Replica Group:
    1.  Change to Placement Edit App Mode (RMB > Application Mode > Placement Edit)
    2.  Display the layers that you want to include in the group
    3.  Select All On in the Find Filter  to enable all objects
    4.  Drag a window over the components, hover over one of the select components and RMB > Place Replicate Create
        - Clines, vias and shapes connected to the components should be highlighted
        - Any objects that were not highlighted (detected) select them now and RMB > Done when finished
    5.  Select the origin for the Place Replica group
    6.  Save a copy of the Place Replica definition (*.mdd)

The group has been created and it can be mirrored with everything attached coming along for the ride.  Once you complete the mirror you can explode the group back to individual objects using RMB > Disband Group on the Group.  It may seem like a lot of steps but I wanted to be as detailed as possible - I use this trick all the time and works well.
    
Hope this helps,
Mike Catrambone

Hi Mike,

This works perfectly and would save me a lot of time.

Thank so much.

Regards,

TiBo