How to launch Web App on power options screens like Login, Lock, Sleep, Restart.

One way that I identified to get a button on the login screen that appears after log off, is to use Pre login agent. I could get the button on that screen and trying to identify ways to launch a web application on click of the button. Also could not get a way to render the button on the login screens that appear after lock, sleep and restart of the system. Appreciate any help on these points.

How to launch Web App on power options screens like Login, Lock, Sleep, Restart.
 
 
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