Its very annoying that you cannot see the alpha parts transparent in blender once you use a real material. The only way I know to make it look transparent means to reduce the alpha of the material to 0 ( and do some other things )
but setting the alpha to 0 results in a g3d file which has opacity=0 for the material (which is correct but annoying )
opacity = 0 ingame means "not visible" :-(
As at least MG does not show opacity below 0.4 anyways thats why I think about setting all materials to opacity=1 automatically if they have a opacity=0.
So suggestions for MG and/or blender ?
Update: I think its best if the blender exporter prevents something like this. He should set the opacity to 1 if it was set to 0.