Try declaring one texture for each hidden Selections:
hiddenSelectionsTextures[]={"\data\objects\GCS\GCS_01_co.paa", "\data\objects\GCS\GCS_02_co.paa", "\data\objects\GCS\GCS_03_co.paa"};
without changes...
hiddenSelectionsTextures[] = {"","",""};
if you only want to change one...
hiddenSelectionsTextures[] = {"\data\objects\GCS\GCS_01_co.paa","",""};
you can also declare hidden Selections in the model.cfg
sections[]=
{
"screen_01",
"screen_02",
"screen_03"
};
You really need to change hiddenSelectionsMaterials?
They are just ideas.
But I think you need to declare 3 hiddenSelectionsTextures.
Sorry for my bad English :)