#201 – Showing a Modal Dialog Using ShowDialog

Rather than using the Window.Show method to show a modeless window, you can use the ShowDialog method to show the window as a modal dialog.

A modal dialog is one that appears in front of all other windows in the application and blocks interaction with all the other windows until the modal dialog is closed.

A modeless window, on the other hand, is one that you can interact with along with other windows in the application.

In the example below, we use the same child window class, but display one window as modeless (using Show) and one as modal (using ShowDialog).

        private void btnModal_Click(object sender, RoutedEventArgs e)
        {
            ChildWindow win = new ChildWindow();
            win.Title = "Modal child - " + DateTime.Now.ToLongTimeString();
            win.ShowDialog();
        }

        private void btnModeless_Click(object sender, RoutedEventArgs e)
        {
            ChildWindow win = new ChildWindow();
            win.Title = "Modeless window - " + DateTime.Now.ToLongTimeString();
            win.Show();
        }

Minimizing a modal window will also minimize its parent.