Hello.
I do this using the uiextras plugin
app.LoadPlugin( "UIExtras" );
function OnStart()
{
lay = app.CreateLayout( "Linear", "VCenter,FillXY" );
btn = app.CreateButton( "Pick Date", 0.3, 0.1 );
btn.SetOnTouch( btn_OnTouch );
lay.AddChild( btn );
app.AddLayout( lay );
uix = app.CreateUIExtras();
}
function btn_OnTouch()
{
picker = uix.CreateDatePickerDialog( "Pick a Date" );
picker.SetOnOk( picker_OnOk );
picker.Show();
}
function picker_OnOk( year, month, day )
{
var date = new Date();
date.setFullYear( year, month, day);
app.ShowPopup( date.toDateString() );
}