I know use below script, there will be an error window alert when @id is not null by using the <error> tag?
<check expr="[@id] != ''">
<error>You must specify a list.</error>
But how a build a confirm window where we can choose "yes" or "no"?
The xtk:job form has a container attribute askConfirmation="true".
It's part of a wizard's soap call, though maybe can be used here.