Fix NULL _Parent and uninitialized parentId

code/nel/src/gui/interface_group.cpp

@@ -622,12 +622,29 @@ namespace NLGUI
 		{
 			std::string parentId;
 
-			if( value != "parent" ){
+			if (value != "parent")
+			{
 				if (_Parent != NULL)
+				{
 					parentId = _Parent->getId() + ":" + value;
+				}
+				else
+				{
+					parentId = "ui:" + value;
+				}
+			}
 			else
+			{
+				if (_Parent)
+				{
 					parentId = _Parent->getId();
 				}
+				else
+				{
+					parentId = value;
+				}
+			}
+
 			CWidgetManager::getInstance()->getParser()->addParentSizeMaxAssociation(this, parentId);
 			return;
 		}