What do you mean by "halt Application window"?
Please check below screenshot for clarification
Is it possible ?
Not with a ScriptUI dialog.
You could create a html5 panel, though.
As c.pfaffenbichler said, you can't do that with the ScriptUI, in fact, you won't be able to really do anything until the script runs it's course, so as mentioned above, it would be best to make an html5 panel, and break up the script into chunks so that the user can interact with the screen.
you might try this ones:
BridgeTalk sounds like a viable choice to me.