Disable a menu item

Hi All, I have a question on how to disable a menu item. I have a File Menu that contains Open, Save, Save As, Close and Exit. When user click an Open Menu it will pop up an openFileDialog and populate a listview with a data. After I succesfully opened my file I want the Open Menu become disable. What kind of Event control or handler can be used to check whether I have succesfully open my file so I can set OpenMenu.enabled = false. or perhaps I can use one of the ListView event controls? Thank you for any hints or ideas.