Unable to bind background color to app variable!

I’m a newbie in Appgyver and I’m really surprised of what you can do with it !

I’m sure that what i’m going to ask exists a hundred percent so, I need to change the background color of a component : it can be a cell, a row, a page layout or any component that has background color, the fact is here :
Capture d’écran 2023-01-20 120819

I cannot find the left button to bind it with variables.

Anyone knows how to do it ?

It looks like this is possible, check out this page here: Change background color