This is needed for implementing reliable serialization of custom translations. As long as they are merely ints they cannot be restored on loading a savegame because the serialization code does not know that these variables are special.
This allows proper dimensions in the stock menus and should make menu layout for mods a lot easier because coordinates are more predictable than with the clean factors.
The feature is opt-in for custom content. As long as only stock elements are used, the menu will be able to switch between both on its own, but as soon as custom classes or custom elements are used, the virtual size must be declared explicitly, defaulting to clean scaling.
