Silverlight stop page closing before being saved

In the old days for WinForms, if your user was creating/editing some information in a DialogBox, it was easy to detect the Window closing and if the data was dirty, ask if they wanted to save.

My question is, how do you approach this scenario in Silverlight where everything seems to be done in UserControls, which have no obvious way of kn开发者_开发百科owing when the page is closing, ie switching to another page within the Silverlight app would simply open a different UserControl without checking the previous UserControl needed saving.

There must be some standard way of achieving this?

If you need to ask the user a question about whether to save or not then you will need to handle this in the browser the onbeforeunload (whilst not a standard event it is supported by those browsers on which Silverlight is officially supported). It may be possible to set up a little javascript to call back into your application when onbeforeunload fires.

That said I'm not a fan of the "Are you sure, you want to lose all that work you've just done" type of question. "Of course I don't want lose it, save it already, as long as I can undo it later if necessary I'm happy".

You can handle the Application.Exit event to execute code on application shut down. Be warned that at this time the networking stack has already shut down so you can't send any messages from the Application.Exit. You cannot cancel the event.

+1 Michael. It is a current limitation of SL. You can however persist to isolated storage from the app exit event, would it be feasible in your app to check if dirty, and if so save to iso storage. Then next time your app loads you could load the dirty data from iso storage ready to carry on editing..?