var d1=app.dialogs.add({name:"Dlg-test1"});
var d2=app.dialogs.add({name:"Dlg-test2"});
var d3=app.dialogs.add({name:"Dlg-test3"});
var d4=app.dialogs.add({name:"Dlg-test4"});
var d5=app.dialogs.add({name:"Dlg-test5"});
var d=app.dialogs;
alert(d.previousItem(d[4]).name);
d1.destroy();
d2.destroy();
d3.destroy();
d4.destroy();
d5.destroy();