[Gmsh] Issues with Gmsh GUI

[Gmsh User]

Please ignore my previous post. The problem was entirely due to :
out1[] = Extrude{0, 0, 0.5} {Surface{6, 11, 16, 21, 26, 30, 34, 38, 42};} ;

I was thinking that the array out1[] will hold the list of volume numbers for
each surface extrusion, but it turned that is not the case.
Anyhow, my coloring questions still remains though. I cannot find a way to color
different physical volumes with different colors for easy recognition and
visualization.
Thanks much for helping out!