Index: wp-admin/edit-comments.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/edit-comments.php	(revision 35051)
+++ wp-admin/edit-comments.php	(revision )
@@ -252,7 +252,18 @@
 			}
 		}
 
+
+		/**
+		 * Filter the array of admin messages for editing comments before display.
+		 *
+		 * @since 4.4.0
+		 *
+		 * @param string[] $messages Array of messages to display, each containing HTML formatting.
+		 */
+		$messages = apply_filters( 'edit_comments_admin_messages', $messages );
+
 		echo '<div id="moderated" class="updated notice is-dismissible"><p>' . implode( "<br/>\n", $messages ) . '</p></div>';
+
 	}
 }
 ?>
Index: wp-admin/edit-tags.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/edit-tags.php	(revision 35051)
+++ wp-admin/edit-tags.php	(revision )
@@ -311,7 +311,17 @@
 	printf( '<span class="subtitle">' . __('Search results for &#8220;%s&#8221;') . '</span>', esc_html( wp_unslash($_REQUEST['s']) ) ); ?>
 </h1>
 
-<?php if ( $message ) : ?>
+<?php
+/**
+ * Filter the admin message for edit-tags.php before display.
+ *
+ * @since 4.4.0
+ *
+ * @param string $message Messages to display containing HTML formatting.
+ */
+$message = apply_filters( 'edit_tag_admin_message', $message );
+
+if ( $message ) : ?>
 <div id="message" class="<?php echo $class; ?> notice is-dismissible"><p><?php echo $message; ?></p></div>
 <?php $_SERVER['REQUEST_URI'] = remove_query_arg( array( 'message', 'error' ), $_SERVER['REQUEST_URI'] );
 endif; ?>
Index: wp-admin/users.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/users.php	(revision 35051)
+++ wp-admin/users.php	(revision )
@@ -460,6 +460,15 @@
 	</div>
 <?php endif;
 
+/**
+ * Filter the array of user admin messages before display.
+ *
+ * @since 4.4.0
+ *
+ * @param string[] $messages Array of messages to display, each containing HTML formatting.
+ */
+$messages = apply_filters( 'users_admin_messages', $messages );
+
 if ( ! empty($messages) ) {
 	foreach ( $messages as $msg )
 		echo $msg;
Index: wp-admin/network/site-settings.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/network/site-settings.php	(revision 35051)
+++ wp-admin/network/site-settings.php	(revision )
@@ -110,6 +110,16 @@
 ?>
 </h2>
 <?php
+
+/**
+ * Filter the array of site settings admin messages before display.
+ *
+ * @since 4.4.0
+ *
+ * @param string[] $messages Array of messages to display, each containing HTML formatting.
+ */
+$messages = apply_filters( 'site_settings_admin_messages', $messages );
+
 if ( ! empty( $messages ) ) {
 	foreach ( $messages as $msg )
 		echo '<div id="message" class="updated notice is-dismissible"><p>' . $msg . '</p></div>';
Index: wp-admin/widgets.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/widgets.php	(revision 35051)
+++ wp-admin/widgets.php	(revision )
@@ -155,7 +155,7 @@
 
 		/**
 		 * Fires immediately after a widget has been marked for deletion.
-		 * 
+		 *
 		 * @since 4.4.0
 		 *
 		 * @param string $widget_id  ID of the widget marked for deletion.
@@ -341,14 +341,42 @@
 ?>
 </h1>
 
-<?php if ( isset($_GET['message']) && isset($messages[$_GET['message']]) ) { ?>
-<div id="message" class="updated notice is-dismissible"><p><?php echo $messages[$_GET['message']]; ?></p></div>
-<?php } ?>
-<?php if ( isset($_GET['error']) && isset($errors[$_GET['error']]) ) { ?>
-<div id="message" class="error"><p><?php echo $errors[$_GET['error']]; ?></p></div>
-<?php } ?>
+<?php
+$message = isset( $_GET['message'] ) && isset( $messages[ $_GET['message'] ] ) ? $messages[ $_GET['message'] ] : '';
 
+/**
+ * Filter the admin message for Widgets before display.
+ *
+ * @since 4.4.0
+ *
+ * @param string $message Messages to display containing HTML formatting.
+ */
+$message = apply_filters( 'widget_admin_message', $message );
+
+if ( $message ):
+?>
+<div id="message" class="updated notice is-dismissible"><p><?php echo $message; ?></p></div>
 <?php
+endif; ?>
+
+<?php
+$error = isset( $_GET['error'] ) && isset( $errors[ $_GET['error'] ] ) ? $errors[ $_GET['error'] ] : '';
+
+/**
+ * Filter the admin error for Widgets before display.
+ *
+ * @since 4.4.0
+ *
+ * @param string $error Messages to display containing HTML formatting.
+ */
+$error = apply_filters( 'widget_admin_error', $error );
+
+if ( $error ):
+?>
+<div id="message" class="error"><p><?php echo $error; ?></p></div>
+<?php
+endif;
+
 /**
  * Fires before the Widgets administration page content loads.
  *
Index: wp-admin/network/site-new.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/network/site-new.php	(revision 35051)
+++ wp-admin/network/site-new.php	(revision )
@@ -160,6 +160,16 @@
 <div class="wrap">
 <h1 id="add-new-site"><?php _e( 'Add New Site' ); ?></h1>
 <?php
+
+/**
+ * Filter the array of new site admin messages before display.
+ *
+ * @since 4.4.0
+ *
+ * @param string[] $messages Array of messages to display, each containing HTML formatting.
+ */
+$messages = apply_filters( 'new_site_admin_messages', $messages );
+
 if ( ! empty( $messages ) ) {
 	foreach ( $messages as $msg )
 		echo '<div id="message" class="updated notice is-dismissible"><p>' . $msg . '</p></div>';
Index: wp-admin/user-new.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/user-new.php	(revision 35051)
+++ wp-admin/user-new.php	(revision )
@@ -257,8 +257,18 @@
 	echo _x( 'Add Existing User', 'user' );
 } ?>
 </h1>
+<?php
 
-<?php if ( isset($errors) && is_wp_error( $errors ) ) : ?>
+/**
+ * Filter the array of error messages for new users before display.
+ *
+ * @since 4.4.0
+ *
+ * @param string[] $messages Array of messages to display, each containing HTML formatting.
+ */
+$errors = apply_filters( 'new_user_admin_errors', $errors );
+
+if ( isset($errors) && is_wp_error( $errors ) ) : ?>
 	<div class="error">
 		<ul>
 		<?php
@@ -268,6 +278,15 @@
 		</ul>
 	</div>
 <?php endif;
+
+/**
+ * Filter the array of user admin messages for new users before display.
+ *
+ * @since 4.4.0
+ *
+ * @param string[] $messages Array of messages to display, each containing HTML formatting.
+ */
+$messages = apply_filters( 'new_user_admin_messages', $messages );
 
 if ( ! empty( $messages ) ) {
 	foreach ( $messages as $msg )
Index: wp-admin/network/site-info.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/network/site-info.php	(revision 35051)
+++ wp-admin/network/site-info.php	(revision )
@@ -153,6 +153,16 @@
 ?>
 </h2>
 <?php
+
+/**
+ * Filter the array of site info admin messages before display.
+ *
+ * @since 4.4.0
+ *
+ * @param string[] $messages Array of messages to display, each containing HTML formatting.
+ */
+$messages = apply_filters( 'site_info_admin_messages', $messages );
+
 if ( ! empty( $messages ) ) {
 	foreach ( $messages as $msg ) {
 		echo '<div id="message" class="updated notice is-dismissible"><p>' . $msg . '</p></div>';
Index: wp-admin/nav-menus.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/nav-menus.php	(revision 35051)
+++ wp-admin/nav-menus.php	(revision )
@@ -593,6 +593,16 @@
 		?>
 	</h2>
 	<?php
+
+	/**
+	 * Filter the array of admin messages for nav menus before display.
+	 *
+	 * @since 4.4.0
+	 *
+	 * @param string[] $messages Array of messages to display, each containing HTML formatting.
+	 */
+	$messages = apply_filters( 'nav_menu_admin_messages', $messages );
+
 	foreach ( $messages as $message ) :
 		echo $message . "\n";
 	endforeach;
Index: wp-admin/upload.php
IDEA additional info:
Subsystem: com.intellij.openapi.diff.impl.patch.CharsetEP
<+>UTF-8
===================================================================
--- wp-admin/upload.php	(revision 35051)
+++ wp-admin/upload.php	(revision )
@@ -283,6 +283,15 @@
 	$_SERVER['REQUEST_URI'] = remove_query_arg(array('message'), $_SERVER['REQUEST_URI']);
 }
 
+/**
+ * Filter the admin message for upload.php before display.
+ *
+ * @since 4.4.0
+ *
+ * @param string $message Messages to display containing HTML formatting.
+ */
+$message = apply_filters( 'upload_admin_message', $message );
+
 if ( !empty($message) ) { ?>
 <div id="message" class="updated notice is-dismissible"><p><?php echo $message; ?></p></div>
 <?php } ?>