Fixed application duplicating save dialog alert

[Hexman768]

Description

• This code change address Application asks user twice if they want to save the current information  #125

Implementation Details

• This code change also greatly improves the functionality of the closing event handlers. Before this change, we would construct a custom closing event arguments model prior to launching the editor closing event handler. After this change, we now can use the existing form closing event model so that we can bubble event attributes back up the stack instead of constructing a new model each time we have to handle a closing event.