init content entity after navbar construction

src/Entity/Window/Tab/History.php

@@ -31,11 +31,11 @@ class History
             \GtkOrientation::VERTICAL
         );
 
-        $this->content = new Content(
+        $this->navbar = new Navbar(
             $this
         );
 
-        $this->navbar = new Navbar(
+        $this->content = new Content(
             $this
         );
 

src/Entity/Window/Tab/History/Content.php

@@ -175,7 +175,6 @@ class Content
 
         else
         {
-            /* @TODO initiation test
             $this->history->navbar->open->gtk->set_sensitive(
                 false
             );
@@ -183,7 +182,6 @@ class Content
             $this->history->navbar->delete->gtk->set_sensitive(
                 false
             );
-            */
         }
     }