Add the following javascript:
var msgValue =app.alert({
cMsg: " Type in your question here",
nIcon: 1,
nType:1,
cTitle: "Message Box"
});
if (msgValue == 1)
app.alert("You clicked ok");
else
app.alert("You clicked cancel");
/****
nIcon , nType can be changed accordingly for different icons (warning, info etc..) & nType can be changed for Yes/No and other options:
****/