I don't. Here's my main level script:

#include "gid01-c.c"
#include "nogouraud-c.c"
#include "sky01-c.c"
#include "tree1-c.c"



STRING* level_str = "GLfirst.WMB";





var myscreenshot_count=0;

function myscreenshot()
{
file_for_screen("shot.png",myscreenshot_count); // saves a screenshot to "shot123.png"
myscreenshot_count+=1;
}



function main()
{

freeze_mode = 1;

gid01_level_state = gid01_level_not_loaded;

warn_level = 2; // announce bad texture sizes and bad wdl code

mouse_mode = 0;

wait(3);

max_entities = 6000;

level_load(level_str);

wait(3);

gid01_level_state = gid01_level_loaded;

video_set(1920,1200,0,1);

d3d_antialias = 1;




on_s = myscreenshot;



freeze_mode = 0;



while(1)
{
if(gid01_level_state != gid01_level_loaded)
{
freeze_mode = 1; // pause the game
while(gid01_level_state != gid01_level_loaded) { wait(1); }
freeze_mode = 0; // resume the game
}
wait(1);
}

}



The gid01 is the default .c template--I just made a copy and dropped it into my work directory.

The nogouraud, sky01 and tree1 are really simple, and in my testing I've tried running the level without those, and removing them has no effect on my level-loading...