Opening Modal/Pop up window and communicate to Task pane

-when app office project run, open modal/popup window first,
modal window contains url page asks user name , password.
authentication taken care third party.
modal window contains 2 buttons ok cancel. on successful authentication,
ok button gets enabled , on clicking of it, user needs return task pane of word.
can functionality achieved? pls provide pointers/guidelines on how open modal window (which should embed url page) , passing data between modal window , task pane.

modal window

 ___________________

|  login pageurl     |
|  ok cancel           |  ->   task pane
_______________

thanks,

josh

we doing research problem. there might delay response. appreciate patience.

Microsoft Office for Developers  ,  Apps for Office and SharePoint  >  Developing Apps for Office 2013