Close all child WPF windows and terminate awaiting code
I am trying to implement a system for closing all modal and non-modal windows in a WPF application (with the exception of the main application window.) When these windows are closed, any code awaiting the result of a dialog should be abandoned.
So far, I’ve considered/attempted two strategies:
- Close and restart the application.
- Close all the windows and rely on task cancellation exceptions to abandon all code that was waiting for dialog results. (It bubbles up to the App level and then becomes handled.)
The first solution definitely gets the application to close and will suffice for automatic logout, but I am extremely uncomfortable with code that continues to execute after the dialog it was waiting for has been closed. Is there a nice way to stop the execution of that code?
The second solution has been working relatively well (calling code is aborted) but has one critical flaw: on occasion, some combination of modal and non-modal windows closing in quick succession will cause the application to lock up on a ShowDialog call. (At least, when you pause execution, that’s where it ends up.) This is strange because breakpoints clearly demonstrate that the Closed event is being raised on all windows that I intend to close. The result that the end user sees is a login screen that cannot be clicked on but can be tabbed into. So strange! Attempts to dispatch the call at different priorities have been unsuccessful, but a Task.Delay for 100ms might have done the trick. (That’s not a real solution, though.)
If each open popup is awaiting a TaskCompletionSource in the background, and, upon completion of the TCS, tries to use the dispatcher to invoke Close on itself, why would one (or more) of the dialogs still be blocking on ShowDialog , even after seeing the Closed event be raised? Is there a way to properly dispatch these calls to Close so they complete successfully? Do I need to be particular about the order in which the windows close?
