Combo + list only values

I want the user being able to only enter values that are presented in list.
I saw another post with an solution. This was 2011.

In grid there’s a excell “coro” which behaves exactly what i need.
Can this be done for normal combo too?

If you don’t need to use “backspace” button in the combo input, you can try the next approach:

combo.getInput().onkeydown = function(){ return false; };