Callback: Additional text in purchase screen

Additional text in purchase screen (23)

This callback is called when TTDPatch displays the vehicle stats of any vehicle in its purchase screen. The return value is the "xx" of a D0xx text ID to be shown below all other stats. The callback is always used when defined, no bit in the action 0 property needs to be set to activate it. As of r1908, text IDs D100..D3FF may also be returned.

How many lines are available depends on the type of vehicle and its other properties, for instance the presence or absence of a "refittable to" line or powered wagons etc. Lines are wrapped automatically, or may be broken explicitly using the newline character 0D.

If cargo FF (buy menu sprite) is handled explicitly for a vehicle, then the varaction 2 handling callback 23 must be in the buy menu varaction 2 chain.