The version 1.4 changelist looks like this so far;
- Added a new attribute; Background, which color the box of expandable item.
- MaskedEnum attribute is replaced by the Enum attribute, which also controls how an enum is displayed.
- Merge the Size attribute with the CollectionConstructor attribute into the new Collection attribute.
- Toolbars are no longer using the toolbar style by default. You can do row of buttons this way.
- Toolbars are now drawn on the header, because they collided with the separator.
- Descriptor color now colors field instead of label. It made no sense to color the label, and was often hard to read.
- Descriptor with only a color no longer pass on an empty name to the label.
- Added a missing constructor in AdvancedInspector attribute.
- Expandable attribute now has the InspectDefaultItems similar to the AdvancedInspector attribute.
- Fixed an error raised when encountering a type with multiple overload of ToString.
- Fixed an issue when undoing creation or deletion of an item in a collection was not properly refreshing it.
- Fixed an issue that prevented proper undoing of collection reordering.
- Added multiple display option to the Enum attribute, see the EnumDisplay enum.
- Added multiple display option to the Collection attribute, see the CollectionDisplay enum.
- Added multiple display option to the Restrict attribute, see the RestrictDisplay enum.
- Added a “Collection Locked” option to the contextual menu, it locks every collection from adding/removing/sorting items.
- Added a Tutorial documentation, which gives steps by steps examples of implementation.
- Fixed an issue that prevented copy pasting AnimationCurve.
- Fixed an issue that custom-made Editor that were not overloading RefreshFields would fail.
- Removed the “EditedTypes” and “EditDerived” from the InspectorEditor, as the CustomEditor attribute values are now used.
I skipped 1.33 because of some major changes in attributes definition. All enum control are now in the EnumAttribute and all collection control are in CollectionAttribute.
Restricted field, Collection and Enum now have display options;

The online documentation have been updated and a first series of basic tutorial have been added; http://lightstrikersoftware.com/docs/AdvancedInspector_Tutorials.pdf
The tutorial are only in their first iterations, and more will be added. Also, if you have issues with some features, I’ll gladly write tutorial specific to your problems.
1.4 should be submitted to the asset store this week.