Hi Hitesh,
What I see happening here is after a popup opens the focus is not returning back to the main window. Hence you are not able to click on any fields.
This appears to be dug to some missing fixes in your system for WDA rendering. It is not issue with the script. This can be confirmed by that fact that everything works fine as long as you do not trigger the popups like Select Position. Right?
Please refer to my earlier response on Jul 3, 2013 1:26 PM .
Hope this helps.
Regards,
Sahir.