Hi @sukhil_sW63MA. It sounds to me like you would need to create an Inventor add-in for something like that, because that is a very specific event to attempt to capture. I am not even sure it would be possible to capture the actual before & after values during that type of event. You would likely have to use the ApplicationEvents.OnDocumentChange event handler, which reacts extremely often to a very wide array of actions, making it relatively complex to use efficiently, without degrading the performance of Inventor. I believe there are also a couple other events (such as UserInputEvents.OnActivateCommand & TransactionEvents.OnCommit) which get triggered by the same actions, and may tell you that a dimension has been edited, but they are even more vague, and offer even less (or none at all) usable 'context info' about those events. I don't think any of those event handlers will give you direct access to the exact dimension object being edited, or the actual value that the user entered while it was being edited.
About all we can do is iterate the dimensions and check the following two property values:
DrawingDimension.ModelValueOverridden
DrawingDimension.OverrideModelValue
I could be wrong though, because I have not attempted monitoring every possible type of event simultaneously in an attempt to catch that very specific event before with an add-in myself.
Wesley Crihfield

(Not an Autodesk Employee)