you should store in a variable the zone that has the focus instead of adding a boolean keyNavigation

tab should also switch the zone

4?
>0 instead of >=1, if it's to check it's not empty

setting the keyNavigation in handleKeys break this binding. Anyways, you can use a single alias to the current zone which should handle the keys instead of having booleans

total 20 wagons in sample zone is divided in 4 rows with 5 wagons each for both portrait and landscape mode. To switch to answer zone when up arrow pressed and current highlited element is in first row i.e.( sampleList.currentIndex <= 4 ).

my point was more to avoid magic numbers and put the variable it corresponds to instead.