Handling the window closing event with WPF / MVVM Light ToolkitI'd like to handle the Closing event (when a user clicks the upper right 'X' button) of my window in order to eventually display a confirm message or/and cancel the closing. I know how to do this in the code-behind: subscribe to the Closing event of the window then use the CancelEventArgs.Cancel property. But I'm using MVVM so I'm not sure it's the good approach. I think the good approach would be
