Sorry guys but I missed your posts!
Stevie G:
I agree I must be more specific:
I am working on a 3D cursor like the one in
UnlimitedDrop if you know. Because I want to have this cursor visible all the time I need to change its Z-Order.
If the 3D cursor consists of 3 separate parts (X, Y and Z axes) then I cannot setup correctly their Z-Order because they must overlap each other in a correct manner (if you have the time please download the program to see what I mean). So I decided to build a single mesh but I need to make white the X-Axis part when the user drags from X-handle for example and so on.