My Script is below:
var myApplicationEventListener = app.eventListeners.add("beforePrint",myEventInfo);
I can popup the message box, while i'm print the doc, but when I get document into a book, then I use print book or print selected document, can't popup a message box, how can I even popup the message box even I print the book or print the selected document???
Thanks for reporting this issue.
verified this as bug inside InDesign. Hence logged bug#3701394 for tracking this issue.
We might get this fixed in next update of InDesign.