- Improves menu expansion code

::

lib/Config/Menu.php

@@ -113,7 +113,7 @@ class Menu {
       )
     );
     add_submenu_page(
-      true,
+      'admin.php?page=mailpoet-subscribers',
       $this->setPageTitle( __('Import')),
       __('Import'),
       'manage_options',
@@ -123,6 +123,7 @@ class Menu {
         'import'
       )
     );
+
     add_submenu_page(
       true,
       $this->setPageTitle(__('Export')),
@@ -393,12 +394,14 @@ class Menu {
   function import() {
     $import = new BootStrapMenu('import');
     $data = $import->bootstrap();
+    $data['sub_menu'] = 'mailpoet-subscribers';
     echo $this->renderer->render('subscribers/importExport/import.html', $data);
   }
 
   function export() {
     $export = new BootStrapMenu('export');
     $data = $export->bootstrap();
+    $data['sub_menu'] = 'mailpoet-subscribers';
     echo $this->renderer->render('subscribers/importExport/export.html', $data);
   }
 
@@ -416,7 +419,8 @@ class Menu {
       'styles' => FormRenderer::getStyles($form),
       'date_types' => Block\Date::getDateTypes(),
       'date_formats' => Block\Date::getDateFormats(),
-      'month_names' => Block\Date::getMonthNames()
+      'month_names' => Block\Date::getMonthNames(),
+      'sub_menu' => 'mailpoet-forms'
     );
 
     echo $this->renderer->render('form/editor.html', $data);