Force compile-time failures for the subtle changes done in the API

src/main/java/org/bukkit/event/block/BlockListener.java

@@ -1,6 +1,7 @@
 package org.bukkit.event.block;
 
 import org.bukkit.event.Listener;
+import org.bukkit.plugin.AuthorNagException;
 
 /**
  * Handles all events thrown in relation to Blocks
@@ -32,10 +33,16 @@ public class BlockListener implements Listener {
      * Called when a block flows (water/lava)
      *
      * @param event Relevant event details
+     * @throws BukkitAuthorNagException 
      */
     public void onBlockFromTo(BlockFromToEvent event) {
+        onBlockFlow(event);
+        throw new AuthorNagException("onBlockFlow has been deprecated, use onBlockFromTo");
     }
 
+    // Prevent compilation of old signatures TODO: Remove after 1.4
+    @Deprecated public final void onBlockFlow(BlockFromToEvent event) {}
+
     /**
      * Called when a block gets ignited
      *

src/main/java/org/bukkit/event/player/PlayerListener.java

@@ -162,4 +162,10 @@ public class PlayerListener implements Listener {
      */
     public void onPlayerBucketEmpty(PlayerBucketEmptyEvent event) {
     }
+
+    // Prevent compilation of old signatures TODO: Remove after 1.4
+    @Deprecated public final void onPlayerQuit(PlayerEvent event) {}
+    @Deprecated public final void onPlayerCommandPreprocess(PlayerChatEvent event) {}
+    @Deprecated public final void onPlayerTeleport(PlayerMoveEvent event) {}
+    @Deprecated public final void onPlayerJoin(PlayerEvent event) {}
 }

src/main/java/org/bukkit/event/server/ServerListener.java

@@ -30,4 +30,8 @@ public class ServerListener implements Listener {
      */
     public void onServerCommand(ServerCommandEvent event) {
     }
+
+    // Prevent compilation of old signatures TODO: Remove after 1.4
+    @Deprecated public final void onPluginDisable(PluginEvent event) {}
+    @Deprecated public final void onPluginEnable(PluginEvent event) {}
 }

src/main/java/org/bukkit/event/vehicle/VehicleListener.java

@@ -75,4 +75,7 @@ public class VehicleListener implements Listener {
      */
     public void onVehicleUpdate(VehicleUpdateEvent event) {
     }
+
+    // Prevent compilation of old signatures TODO: Remove after 1.4
+    @Deprecated public final void onVehicleUpdate(VehicleEvent event) {}
 }

src/main/java/org/bukkit/event/world/WorldListener.java

@@ -38,4 +38,8 @@ public class WorldListener implements Listener {
      */
     public void onWorldLoad(WorldLoadEvent event) {
     }
+
+    // Prevent compilation of old signatures TODO: Remove after 1.4
+    @Deprecated public final void onWorldLoad(WorldEvent event) {}
+    @Deprecated public final void onWorldSave(WorldEvent event) {}
 }