You are very lucky! :) Must be works in V3...
http://kyticka.webzdarma.cz/3d/moi/#SelectClosedCurves
put that in the ShortCut Options or Press Tab and Copy/Past it then Press Enter

script:var curves = moi.geometryDatabase.getObjects().getCurves(); for ( var i = 0; i < curves.length; ++i ) if ( curves.item(i).isClosed ) curves.item(i).selected = true;