Unity Inspector Custom Editor GUILayout broken

Hi,
trying to create a Toolbar centered within the editor window, but cant get it work...
Its supposed to look like Unitys Terrain Editor Toolbar

but it looks like this


Code:

Code (CSharp):

1.        public override void OnInspectorGUI()
2.         {
3.             if (!EditorGUIUtility.wideMode)
4.             {
5.                 EditorGUIUtility.wideMode = true;
6.                 EditorGUIUtility.labelWidth = EditorGUIUtility.currentViewWidth - 212;
7.             }
8.  
9.             // Toolbar
10.             //
11.  
12.             GUILayout.BeginVertical(GUILayout.Height(100));
13.  
14.             GUILayout.BeginArea(new Rect(0.25f * Screen.width, 0.01f * Screen.height, 0.5f * Screen.width, 0.02f * Screen.height));
15.             toolbarSelected = GUILayout.Toolbar(toolbarSelected, toolBarContent, GUILayout.Width(0.5f * Screen.width), GUILayout.Height(0.02f * Screen.height));
16.             GUILayout.EndArea();
17.  
18.             GUILayout.EndVertical();
19.         }

What do i need to do to make GUILayout.BeginArea(new Rect()) shown inside the editor window and not somewhere else?