diff --git a/application/applicationextension.inc.php b/application/applicationextension.inc.php
index 68da0a5d0..0579a6bd0 100644
--- a/application/applicationextension.inc.php
+++ b/application/applicationextension.inc.php
@@ -1101,7 +1101,9 @@ class JSButtonItem extends JSPopupMenuItem
  * @api
  * @package     Extensibility
  * @since 2.0
- * @deprecated since 3.0.0 use iPageUIBlockExtension instead
+ * @deprecated 3.0.0 If you need to include:
+ *   * JS/CSS files/snippets, use {@see \iBackofficeLinkedScriptsExtension}, {@see \iBackofficeLinkedStylesheetsExtension}, etc instead
+ *   * HTML (and optionally JS/CSS), use {@see \iPageUIBlockExtension} to manipulate {@see \Combodo\iTop\Application\UI\Base\UIBlock} instead
  */
 interface iPageUIExtension
 {
@@ -1252,6 +1254,119 @@ abstract class AbstractPageUIBlockExtension implements iPageUIBlockExtension
 	}
 }
 
+/**
+ * Implement this interface to add script (JS) files to the backoffice pages
+ *
+ * @see \iTopWebPage::$a_linked_scripts
+ * @api
+ * @since 3.0.0
+ */
+interface iBackofficeLinkedScriptsExtension
+{
+	/**
+	 * @see \iTopWebPage::$a_linked_scripts Each script will be included using this property
+	 * @return array An array of absolute URLs to the files to include
+	 */
+	public function GetLinkedScriptsAbsUrls(): array;
+}
+
+/**
+ * Implement this interface to add inline script (JS) to the backoffice pages' head.
+ * Will be executed first, BEFORE the DOM interpretation.
+ *
+ * @see \iTopWebPage::$a_early_scripts
+ * @api
+ * @since 3.0.0
+ */
+interface iBackofficeEarlyScriptExtension
+{
+	/**
+	 * @see \iTopWebPage::$a_early_scripts
+	 * @return string
+	 */
+	public function GetEarlyScript(): string;
+}
+
+/**
+ * Implement this interface to add inline script (JS) to the backoffice pages that will be executed immediately, without waiting for the DOM to be ready.
+ *
+ * @see \iTopWebPage::$a_scripts
+ * @api
+ * @since 3.0.0
+ */
+interface iBackofficeScriptExtension
+{
+	/**
+	 * @see \iTopWebPage::$a_scripts
+	 * @return string
+	 */
+	public function GetScript(): string;
+}
+
+/**
+ * Implement this interface to add inline script (JS) to the backoffice pages that will be executed right when the DOM is ready.
+ *
+ * @see \iTopWebPage::$a_init_scripts
+ * @api
+ * @since 3.0.0
+ */
+interface iBackofficeInitScriptExtension
+{
+	/**
+	 * @see \iTopWebPage::$a_init_scripts
+	 * @return string
+	 */
+	public function GetInitScript(): string;
+}
+
+/**
+ * Implement this interface to add inline script (JS) to the backoffice pages that will be executed slightly AFTER the DOM is ready (just after the init. scripts).
+ *
+ * @see \iTopWebPage::$a_ready_scripts
+ * @api
+ * @since 3.0.0
+ */
+interface iBackofficeReadyScriptExtension
+{
+	/**
+	 * @see \iTopWebPage::$a_ready_scripts
+	 * @return string
+	 */
+	public function GetReadyScript(): string;
+}
+
+/**
+ * Implement this interface to add stylesheets (CSS) to the backoffice pages
+ *
+ * @see \iTopWebPage::$a_linked_stylesheets
+ * @api
+ * @since 3.0.0
+ */
+interface iBackofficeLinkedStylesheetsExtension
+{
+	/**
+	 * @see \iTopWebPage::$a_linked_stylesheets
+	 * @return array An array of absolute URLs to the files to include
+	 */
+	public function GetLinkedStylesheetsAbsUrls(): array;
+}
+
+/**
+ * Implement this interface to add inline style (CSS) to the backoffice pages' head.
+ *
+ * @see \iTopWebPage::$a_styles
+ * @api
+ * @since 3.0.0
+ */
+interface iBackofficeStyleExtension
+{
+	/**
+	 * @see \iTopWebPage::$a_styles
+	 * @return string
+	 */
+	public function GetStyle(): string;
+}
+
 /**
  * Implement this interface to add content to any enhanced portal page
  *
diff --git a/sources/application/WebPage/iTopWebPage.php b/sources/application/WebPage/iTopWebPage.php
index 318af9c42..1430101ce 100644
--- a/sources/application/WebPage/iTopWebPage.php
+++ b/sources/application/WebPage/iTopWebPage.php
@@ -802,6 +802,45 @@ HTML;
 		$oPrintHeader = null;
 
 		// Prepare internal parts (js files, css files, js snippets, css snippets, ...)
+		// - API: External script files
+		/** @var \iBackofficeLinkedScriptsExtension $oExtensionInstance */
+		foreach (MetaModel::EnumPlugins('iBackofficeLinkedScriptsExtension') as $oExtensionInstance) {
+			foreach ($oExtensionInstance->GetLinkedScriptsAbsUrls() as $sScriptUrl) {
+				$this->add_linked_script($sScriptUrl);
+			}
+		}
+		// - API: Early inline scripts
+		/** @var \iBackofficeEarlyScriptExtension $oExtensionInstance */
+		foreach (MetaModel::EnumPlugins('iBackofficeEarlyScriptExtension') as $oExtensionInstance) {
+			$this->add_early_script($oExtensionInstance->GetEarlyScript());
+		}
+		// - API: Inline scripts
+		/** @var \iBackofficeScriptExtension $oExtensionInstance */
+		foreach (MetaModel::EnumPlugins('iBackofficeScriptExtension') as $oExtensionInstance) {
+			$this->add_early_script($oExtensionInstance->GetScript());
+		}
+		// - API: Init. scripts
+		/** @var \iBackofficeInitScriptExtension $oExtensionInstance */
+		foreach (MetaModel::EnumPlugins('iBackofficeInitScriptExtension') as $oExtensionInstance) {
+			$this->add_init_script($oExtensionInstance->GetInitScript());
+		}
+		// - API: Ready scripts
+		/** @var \iBackofficeReadyScriptExtension $oExtensionInstance */
+		foreach (MetaModel::EnumPlugins('iBackofficeReadyScriptExtension') as $oExtensionInstance) {
+			$this->add_ready_script($oExtensionInstance->GetReadyScript());
+		}
+		// - API: External stylesheet files
+		/** @var \iBackofficeLinkedStylesheetsExtension $oExtensionInstance */
+		foreach (MetaModel::EnumPlugins('iBackofficeLinkedStylesheetsExtension') as $oExtensionInstance) {
+			foreach ($oExtensionInstance->GetLinkedStylesheetsAbsUrls() as $sStylesheetUrl) {
+				$this->add_linked_stylesheet($sStylesheetUrl);
+			}
+		}
+		// - API: Inline style
+		/** @var \iBackofficeStyleExtension $oExtensionInstance */
+		foreach (MetaModel::EnumPlugins('iBackofficeStyleExtension') as $oExtensionInstance) {
+			$this->add_style($oExtensionInstance->GetStyle());
+		}
 		// - Generate necessary dict. files
 		if ($this->bAddJSDict) {
 			$this->output_dict_entries();