Callback: Protect building conditionally
Protect building conditionally (143)
This callback is called when someone tries to remove the building from the map. You can use this callback to prevent the town or AI players from removing the building if certain conditions are met. You can return 0 to allow the destruction, or 1 to disallow it, except for human players, who can always remove any building.
If you always return 1 from this callback, you achieve the same effect as turning on bit 1 of property 19. When this callback is enabled, bit 1 of property 19 is ignored. If the callback fails, the destruction is allowed.
For multi-tile buildings, the callback will be called for the type of the tile the player wants to destroy. Therefore, to get consistent behaviour, you must enable this callback for every tile and respond it the same way no matter which tile it is called for.
Since TTDPatch 2.6 r1705, you can use this callback to prevent building "town" industries (banks, water towers, etc.) over your house. The lowest byte of variable 10 is zero for "normal" demolition and one when TTD wants to remove the house for the sake of a new industry. Other values of variable 10 are reserved for future use.