C# Wpf App e.Cancel = true unable to use! looking for keep application running in tray-CodePudding

I'm unable to use the e.Cancel = true; in c# wpf its returning this error:

CS1061 'FormClosedEventArgs' does not contain a definition for 'Cancel' and no accessible extension method 'Cancel' accepting a first argument of type 'FormClosedEventArgs' could be found (are you missing a using directive or an assembly reference?)

How do I solve it? looking for a quick solution or do I've any way to keep the application running on the tray?

CodePudding user response：

In the XAML designer or in code behind of the Window element you need to add an event handler for the Closing event.

<Window ... Closing="Window_Closing">
    ...
</Window>

Here is the code for a Closing event handler method for WPF applications which will ask the user a question if they really want to close the application.

private void Window_Closing(object sender, System.ComponentModel.CancelEventArgs e)
{
    // If user clicks No the application stays open
    if (MessageBox.Show(
        "Are you sure you want to exit the application?",
        "Confirm Exit:",
        MessageBoxButton.YesNo,
        MessageBoxImage.Information) == MessageBoxResult.No)
    {
        e.Cancel = true;
        // Keep application from closing
    }
    // Else the application closes    
}

CodePudding user response：

You likely want to handle the FormClosing event instead - FormClosingEventArgs does have a Cancel property you can use to prevent the window from being closed.