function SelectTransparency() {
var idChnl = charIDToTypeID( "Chnl" );
var actionSelect = new ActionReference();
actionSelect.putProperty( idChnl, charIDToTypeID( "fsel" ) );
var actionTransparent = new ActionReference();
actionTransparent.putEnumerated( idChnl, idChnl, charIDToTypeID( "Trsp" ) );
var actionDesc = new ActionDescriptor();
actionDesc.putReference( charIDToTypeID( "null" ), actionSelect );
actionDesc.putReference( charIDToTypeID( "T " ), actionTransparent );
executeAction( charIDToTypeID( "setd" ), actionDesc, DialogModes.NO );
}