It seems as Cubase resets the mouse cursor automatically on mouse movement, thus using Component::setMouseCursor simply makes the cursor change for a split second, more like a flicker, before going back to default cursor.
The only remedy i could find is to keep forcing setMouseCursor on mouseMove and commenting out the check inside setMouseCursor for if(cursor != newCursor), but i rather not do that.
Any ideas? It works as intended in other DAWs, seems only cubase has this behaviour.