App.open not responding if called from inside onclick()

Question

Hi all.
Working on a script for InDesign CC 2014 I found this problem : if I call app.open() from inside button.onclick() it stops and nothing happens. Since I'm a beginner with Javascript I'm probably doing something wrong, but I can not figure out where I'm wrong. If executed without onclick it works....
There is another method to achieve the same result?
As my project is still under construction, I place only the portion of code relating to the problem.
I hope someone can help me, I can not get out of this hitch.
Thanks in advance.
var book_info;
var w1 = new Window ("dialog", "TEST");
    w1.minimumSize.height = 50;
    w1.minimumSize.width = 50;
     var p1 = w1.add ("panel");
        sel_button = p1.add ("button", undefined, "Open a book");
     var g1 = w1.add ("group");
        g1.add("button", undefined, "Cancel");
        g1.add("button", undefined, "OK");
sel_button.onClick = function(){
    var theFile = File.openDialog ("Select the book file to open...");
    get_data(theFile);
        alert(book_info.filePath + "\r" + book_info.name);
    book_info.close();
w1.show();
function get_data(data) {
    app.open(data);
    book_info = app.activeBook;
        alert("INSIDE FUNCTION" + book_info.filePath + "\r" + book_info.name);
    return data;

Answer 1

Thanks,Loic.Aigon
A better solution than mine. I just used a variable set inside the select button and check for the value after the window close. You can use different variables for different buttons. The approach is quite  similar. Reusing Loic.Aigon code:
var book_info;  
var theFile;
var getData;
var w1 = new Window ("dialog", "TEST");  
    w1.minimumSize.height = 50;  
    w1.minimumSize.width = 50;  
    var p1 = w1.add ("panel");  
        sel_button = p1.add ("button", undefined, "Open a book");  
    var g1 = w1.add ("group");  
        g1.add("button", undefined, "Cancel");  
        g1.add("button", undefined, "OK");  
sel_button.onClick = function(){  
    theFile = File.openDialog ("Select the book file to open..."); 
  getData =1;        
  w1.close(1);
w1.show()
if (  getData ==1) {
  if ( theFile ) {
  get_data(theFile);  
function get_data(data) {  
    app.open(data);  
    book_info = app.activeBook;  
        alert("INSIDE FUNCTION" + book_info.filePath + "\r" + book_info.name);  
    return data;