Is it possible to create a solid and put it in an other folder than default folder "Solids"?
Something like this should work:
var otherFolder = app.project.item(1);
var myComp = app.project.item(2);
var mySolid = myComp.layers.addSolid([1,1,1],"Solid 1",myComp.width,myComp.height,1,myComp.duration);
mySolid.source.parentFolder = otherFolder;
Europe, Middle East and Africa