diff --git a/core/attributedef.class.inc.php b/core/attributedef.class.inc.php
index 06f98fa2c..df5d060bf 100644
--- a/core/attributedef.class.inc.php
+++ b/core/attributedef.class.inc.php
@@ -1660,7 +1660,12 @@ class AttributeLinkedSet extends AttributeDefinition
 	 */
 	public function GetDisplayStyle()
 	{
-		return $this->GetOptional('display_style', LINKSET_DISPLAY_STYLE_TAB);
+		$sDisplayStyle = $this->GetOptional('display_style', LINKSET_DISPLAY_STYLE_TAB);
+		if ($sDisplayStyle === '') {
+			$sDisplayStyle = LINKSET_DISPLAY_STYLE_TAB;
+		}
+
+		return $sDisplayStyle;
 	}
 
 	/**
diff --git a/sources/Application/UI/Links/Direct/BlockDirectLinksEditTable.php b/sources/Application/UI/Links/Direct/BlockDirectLinksEditTable.php
index 9af91f7eb..0e4ff4f13 100644
--- a/sources/Application/UI/Links/Direct/BlockDirectLinksEditTable.php
+++ b/sources/Application/UI/Links/Direct/BlockDirectLinksEditTable.php
@@ -16,7 +16,6 @@ use Combodo\iTop\Application\UI\Base\Component\Panel\PanelUIBlockFactory;
 use Combodo\iTop\Application\UI\Base\Component\Toolbar\Toolbar;
 use Combodo\iTop\Application\UI\Base\Component\Toolbar\ToolbarUIBlockFactory;
 use Combodo\iTop\Application\UI\Base\Layout\UIContentBlock;
-use Combodo\iTop\Service\Links\LinkSetModel;
 use ConfigException;
 use CoreException;
 use CoreUnexpectedValue;
@@ -24,6 +23,7 @@ use DBObjectSet;
 use Dict;
 use DictExceptionMissingString;
 use Exception;
+use iDBObjectSetIterator;
 use MetaModel;
 use MySQLException;
 use UILinksWidgetDirect;
@@ -134,7 +134,7 @@ class BlockDirectLinksEditTable extends UIContentBlock
 	 *
 	 * @return void
 	 */
-	public function InitTable(WebPage $oPage, DBObjectSet $oValue, string $sFormPrefix)
+	public function InitTable(WebPage $oPage, iDBObjectSetIterator $oValue, string $sFormPrefix)
 	{
 		$this->sInputName = $sFormPrefix.'attr_'.$this->oUILinksDirectWidget->GetAttCode();
 		$this->sWizHelper = 'oWizardHelper'.$sFormPrefix;
@@ -239,7 +239,7 @@ class BlockDirectLinksEditTable extends UIContentBlock
 	 * @throws MySQLException
 	 * @throws Exception
 	 */
-	private function GetTableRows(\WebPage $oPage, \DBObjectSet $oValue): array
+	private function GetTableRows(\WebPage $oPage, iDBObjectSetIterator $oValue): array
 	{
 		// result data
 		$aRows = array();