Setting DialogResult only after ShowDialog() in WPF

Question

I have a window that I sometimes open using Show() and sometimes using ShowDialog(). In the second case, the returned dialog result is important for me. But if I set the DialogResult after calling Show() I get an InvalidOperationException. Is there a way to find out which method was used to open the window and set or not the DialogResult accordingly? Or is there another way?

Of course I know I can catch and ignore the exception, but I don't like this solution.

Answer 1

How about just setting this.DialogResult = DialogResult.blah in the form closing event?

Answer 2

Use System.Windows.Interop.ComponentDispatcher.IsThreadModal inside the window to determine if it runs on a modal thread or not.

Answer 3

If you look at set_DialogResult in Reflector, it checks _showingAsDialog to determine whether the dialog is modal. Unfortunately this is a private field.

Do you always construct a new instance of the window before calling Show()/ShowDialog(). If so, you could pass an argument to the constructor indicating how it is to be shown.

Answer 4

 if (this.Modal)
            {
                MessageBox.Show("Dialog");
            }
            else
            {
                MessageBox.Show("Form");
            }

Answer 5

You can use the Form.Modal property to check the kind of usage.

In the case of using Form.Show() you have to use another way to let the caller know of any results of the Form.

Is there a reason to use both ways of showing the form?