gui troubles

Easiest way is to attach all your entities which are named "track_straight" etc... to a hidden, global TRACKpivot :

global TRACKpivot = createpivot()
hideentity TRACKpivot
loadmesh( "track_straight", TRACKpivot )
loadmesh( "track_c_right", TRACKpivot )

Then do this ..

t.track=New track
ent = findchild( TRACKpivot, temp_text2 )
t\ent=CopyEntity ( ent )
t\mat="metal"