in model/src/main/java/jetbrains/jetpad/model/composite/Composites.java [435:449]
CompositeT lastFocusable(CompositeT v, boolean deepest) {
List<CompositeT> children = v.children();
for (int i = children.size() - 1; i >= 0; i--) {
CompositeT cv = children.get(i);
if (!cv.visible().get()) continue;
if (!deepest && cv.focusable().get()) return cv;
CompositeT result = lastFocusable(cv, deepest);
if (result != null) return result;
}
if (v.focusable().get()) return v;
return null;
}