diff --git a/contrib/home/main.php b/contrib/home/main.php
index 43ece3f4..f46c6238 100644
--- a/contrib/home/main.php
+++ b/contrib/home/main.php
@@ -16,7 +16,7 @@
 */
 
 class Home extends SimpleExtension {
-	public function onInitExt($event) {
+	public function onInitExt(InitExtEvent $event) {
 		global $config;
 		$config->set_default_string("home_links", '[$base/post/list|Posts]
 [$base/comment/list|Comments]
@@ -24,7 +24,8 @@ class Home extends SimpleExtension {
 [$base/wiki|Wiki]
 [$base/wiki/more|»]');
 	}
-	public function onPageRequest($event) {
+
+	public function onPageRequest(PageRequestEvent $event) {
 		global $config, $page;
 		if($event->page_matches("home")) {
 			$base_href = $config->get_string('base_href');
@@ -38,7 +39,7 @@ class Home extends SimpleExtension {
 		}
 	}
 
-	public function onSetupBuilding($event) {
+	public function onSetupBuilding(SetupBuildingEvent $event) {
 		$counters = array();
 		foreach(glob("ext/home/counters/*") as $counter_dirname) {
 			$name = str_replace("ext/home/counters/", "", $counter_dirname);
@@ -53,8 +54,7 @@ class Home extends SimpleExtension {
 	}
 
 
-	private function get_body()
-	{
+	private function get_body() {
 		// returns just the contents of the body
 		global $database;
 		global $config;
diff --git a/ext/alias_editor/main.php b/ext/alias_editor/main.php
index dc12c5c1..3b9b1b27 100644
--- a/ext/alias_editor/main.php
+++ b/ext/alias_editor/main.php
@@ -22,14 +22,11 @@ class AddAliasEvent extends Event {
 
 class AddAliasException extends SCoreException {}
 
-class AliasEditor implements Extension {
-	var $theme;
-
-	public function receive_event(Event $event) {
+class AliasEditor extends SimpleExtension {
+	public function onPageRequest(PageRequestEvent $event) {
 		global $config, $database, $page, $user;
-		if(is_null($this->theme)) $this->theme = get_theme_object($this);
 
-		if(($event instanceof PageRequestEvent) && $event->page_matches("alias")) {
+		if($event->page_matches("alias")) {
 			if($event->get_arg(0) == "add") {
 				if($user->is_admin()) {
 					if(isset($_POST['oldtag']) && isset($_POST['newtag'])) {
@@ -104,23 +101,24 @@ class AliasEditor implements Extension {
 				}
 			}
 		}
+	}
 
-		if($event instanceof AddAliasEvent) {
-			global $database;
-			$pair = array($event->oldtag, $event->newtag);
-			if($database->db->GetRow("SELECT * FROM aliases WHERE oldtag=? AND lower(newtag)=lower(?)", $pair)) {
-				throw new AddAliasException("That alias already exists");
-			}
-			else {
-				$database->Execute("INSERT INTO aliases(oldtag, newtag) VALUES(?, ?)", $pair);
-				log_info("alias_editor", "Added alias for {$event->oldtag} -> {$event->newtag}");
-			}
+	public function onAddAlias(AddAliasEvent $event) {
+		global $database;
+		$pair = array($event->oldtag, $event->newtag);
+		if($database->db->GetRow("SELECT * FROM aliases WHERE oldtag=? AND lower(newtag)=lower(?)", $pair)) {
+			throw new AddAliasException("That alias already exists");
 		}
+		else {
+			$database->Execute("INSERT INTO aliases(oldtag, newtag) VALUES(?, ?)", $pair);
+			log_info("alias_editor", "Added alias for {$event->oldtag} -> {$event->newtag}");
+		}
+	}
 
-		if($event instanceof UserBlockBuildingEvent) {
-			if($user->is_admin()) {
-				$event->add_link("Alias Editor", make_link("alias/list"));
-			}
+	public function onUserBlockBuilding(UserBlockBuildingEvent $event) {
+		global $user;
+		if($user->is_admin()) {
+			$event->add_link("Alias Editor", make_link("alias/list"));
 		}
 	}
 
@@ -143,5 +141,4 @@ class AliasEditor implements Extension {
 		}
 	}
 }
-add_event_listener(new AliasEditor());
 ?>
diff --git a/ext/comment/main.php b/ext/comment/main.php
index 7e518dc2..36196ede 100644
--- a/ext/comment/main.php
+++ b/ext/comment/main.php
@@ -111,7 +111,7 @@ class CommentList extends SimpleExtension {
 		}
 	}
 
-	public function onPageRequest($event) {
+	public function onPageRequest(PageRequestEvent $event) {
 		global $page, $user;
 		if($event->page_matches("comment")) {
 			if($event->get_arg(0) == "add") {
@@ -151,7 +151,7 @@ class CommentList extends SimpleExtension {
 		}
 	}
 
-	public function onPostListBuilding($event) {
+	public function onPostListBuilding(PostListBuildingEvent $event) {
 		global $config;
 		$cc = $config->get_int("comment_count");
 		if($cc > 0) {
@@ -162,14 +162,14 @@ class CommentList extends SimpleExtension {
 		}
 	}
 
-	public function onUserPageBuilding(Event $event) {
+	public function onUserPageBuilding(UserPageBuildingEvent $event) {
 		$i_days_old = ((time() - strtotime($event->display_user->join_date)) / 86400) + 1;
 		$i_comment_count = Comment::count_comments_by_user($event->display_user);
 		$h_comment_rate = sprintf("%.1f", ($i_comment_count / $i_days_old));
 		$event->add_stats("Comments made: $i_comment_count, $h_comment_rate per day");
 	}
 
-	public function onDisplayingImage($event) {
+	public function onDisplayingImage(DisplayingImageEvent $event) {
 		$this->theme->display_image_comments(
 			$event->image,
 			$this->get_comments($event->image->id),
@@ -177,7 +177,7 @@ class CommentList extends SimpleExtension {
 		);
 	}
 
-	public function onImageDeletion($event) {
+	public function onImageDeletion(ImageDeletionEvent $event) {
 		global $database;
 		$image_id = $event->image->id;
 		$database->Execute("DELETE FROM comments WHERE image_id=?", array($image_id));
@@ -185,17 +185,17 @@ class CommentList extends SimpleExtension {
 	}
 
 	// TODO: split akismet into a separate class, which can veto the event
-	public function onCommentPosting($event) {
+	public function onCommentPosting(CommentPostingEvent $event) {
 		$this->add_comment_wrapper($event->image_id, $event->user, $event->comment, $event);
 	}
 
-	public function onCommentDeletion($event) {
+	public function onCommentDeletion(CommentDeletionEvent $event) {
 		global $database;
 		$database->Execute("DELETE FROM comments WHERE id=?", array($event->comment_id));
 		log_info("comment", "Deleting Comment #{$event->comment_id}");
 	}
 
-	public function onSetupBuilding($event) {
+	public function onSetupBuilding(SetupBuildingEvent $event) {
 		$sb = new SetupBlock("Comment Options");
 		$sb->add_bool_option("comment_anon", "Allow anonymous comments: ");
 		$sb->add_bool_option("comment_captcha", "<br>Require CAPTCHA for anonymous comments: ");
@@ -213,7 +213,7 @@ class CommentList extends SimpleExtension {
 		$event->panel->add_block($sb);
 	}
 
-	public function onSearchTermParse($event) {
+	public function onSearchTermParse(SearchTermParseEvent $event) {
 		$matches = array();
 		if(preg_match("/comments(<|>|<=|>=|=)(\d+)/", $event->term, $matches)) {
 			$cmp = $matches[1];
diff --git a/ext/ext_manager/main.php b/ext/ext_manager/main.php
index 8ee0212b..3350ed75 100644
--- a/ext/ext_manager/main.php
+++ b/ext/ext_manager/main.php
@@ -87,7 +87,7 @@ class ExtensionInfo {
 }
 
 class ExtManager extends SimpleExtension {
-	public function onPageRequest($event) {
+	public function onPageRequest(PageRequestEvent $event) {
 		global $page, $user;
 		if($event->page_matches("ext_manager")) {
 			if($user->is_admin()) {
@@ -127,7 +127,7 @@ class ExtManager extends SimpleExtension {
 		}
 	}
 
-	public function onUserBlockBuilding($event) {
+	public function onUserBlockBuilding(UserBlockBuildingEvent $event) {
 		global $user;
 		if($user->is_admin()) {
 			$event->add_link("Extension Manager", make_link("ext_manager"));