How can we get value inside dhtmlxWindow

Hi everyone! I have a problem with dhtmlxWindows. This is my scene:

I have a simple HTML page with a button and text field. When button clicked, one dhtmlxwindow is opened.(it attach a URL) In this, I have one text field, and button OK. My probem is that, when i fill into textbox and click OK button in dhtmlxWindow, i can’t pass value from this textbox to the other in the parent page.


Possibly something as follows:

parent.document.getElementById(…).value = document.getElementById(…).value;