My approach when using ASP.Net for pages that simply edit a single row in a table (not insert or delete) is to have the DetailsView or FormView launch in Edit mode, with the standard link buttons labelled Update and Cancel at the bottom. If the user closes or navigates away, no data change happens - which seems very intuitive to me (and requires no code). The suggested way feels a bit like leaving the car in Drive when you stop and having it roll away when you get out of it.
Are my colleague's suggestions reasonable, or do they reflect a lack of experience with web applications? To me, these suggestions are not just inappropriate to the browser app situation, they are actually harmful. It would add lots of needless and error-prone development for me. How can I approach this? My manager has not heard these one to one discussions and likely has no opinion, but I will bring it up when possible.