Design Studio how to get the Prompt dialog popup

I've design studio application based on Bex query with DS Load query in script 'false'. Query has mandatory variables. When application launches, variable screen is displayed on entire screen. I would like to get it as a popup. I tried below steps.

1. Change the DS Load in script to 'true'

2. Call below statements in On Startup event

APPLICATION.openPromptDialog(500, 500);

DS_1.loadDatasource();

It opens the blank screen when application launches and nothing happens. Any idea how to display the variables in popup when the application launch first time.

Question 2: I would like to have dimension filter smaller in height. When I reduces the height to 30px, I get the scroll bar to extreme right of dimension filter. Any idea what CSS should be implemented to reduce the height without getting scroll bar to right. We're on 1.3 SP02.

Thanks,

Milind