Hi
Trying to add a mask to the Clip preview window can be difficult and more so if you are using dual preview windows. It can be made easier if you Undock and enlarge the clip preview window...
e.g. Normal size.... Not that easy to see the outline and points get quite close together and not very precise.........
By clicking the little diagonal arrow in the top right hand corner of the window you can expand the preview window and even make it full screen. The points of the mask can then be much more detailed......
This is the SAME mask in normal Clip preview....This would almost impossible to do at this size.......
Hope this helps
Nat