Steps to repro:
- Launch unity
- Add a 3D Game object
- In the inspector click on mesh options button

Note that we get an error in the console
InvalidOperationException: Operation is not valid due to the current state of the object
System.Collections.Generic.Stack`1[System.Boolean].Pop ()
UnityEditor.EditorGUI.EndDisabledGroup () (at /Users/builduser/buildslave/unity/build/Editor/Mono/EditorGUI.cs:211)
UnityEditor.EditorGUI+DisabledGroupScope.CloseScope () (at /Users/builduser/buildslave/unity/build/Editor/Mono/EditorGUI.cs:197)
UnityEngine.GUI+Scope.Dispose ()
UnityEditor.Editor.OptimizedInspectorGUIImplementation (Rect contentRect) (at /Users/builduser/buildslave/unity/build/artifacts/generated/common/editor/EditorBindings.gen.cs:234)
UnityEditor.GenericInspector.OnOptimizedInspectorGUI (Rect contentRect) (at /Users/builduser/buildslave/unity/build/Editor/Mono/Inspector/GenericInspector.cs:33)
UnityEditor.InspectorWindow.DrawEditor (UnityEditor.Editor editor, Int32 editorIndex, Boolean rebuildOptimizedGUIBlock, System.Boolean& showImportedObjectBarNext, UnityEngine.Rect& importedObjectBarRect) (at /Users/builduser/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:1211)
UnityEditor.InspectorWindow.DrawEditors (UnityEditor.Editor[] editors) (at /Users/builduser/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:1028)
UnityEditor.InspectorWindow.OnGUI () (at /Users/builduser/buildslave/unity/build/Editor/Mono/Inspector/InspectorWindow.cs:352)
System.Reflection.MonoMethod.Invoke (System.Object obj, BindingFlags invokeAttr, System.Reflection.Binder binder, System.Object[] parameters, System.Globalization.CultureInfo culture) (at /Users/builduser/buildslave/mono/build/mcs/class/corlib/System.Reflection/MonoMethod.cs:222)

screencast:
http://screencast.com/t/OjYDYEFqHt