How to make a specific task to run till the app is closed by the user

Hey I tried to keep on changing the back ground of my app UNTIL THE APP IS CLOSED BY THE USER , but I am not able to do that ...

FOR THIS I HAVE USED A EXTENSION
LINK FOR THE EXTENSION : https://community.thunkable.com/t/free-animation-color-background-extension/5275


pls help AND I AM waiting eagerly FOR YOU REPLIES

Use the Clock.1 Timer block to do this, the code inside it is repeated as long as Clock1.timer Enabled is true, the code inside is repeated after every Clock1.Timer Interval milliseconds. Set Timer Always Fires to false if you don't want it to be executed when your app is closed.

i will try and reply
thank you