How to know if Status Bar is collapsed or Not using StatusbarService

I am flashing notification in my App.It shows notification icon in the status bar.
When user Slides the Status Bar down, it shows the same Icon + some text

I want to change the Icon which appears when user slide the bar down. For this i need to have some kind of receiver which can tell me when Status bar is slided down and i will issue the notify with different icon.

Problem is how to know when Status Bar is slided down by the user?? Please give me some pointers.