How do I work with WIndows Forms in WPF?

[complete]

In my WPF program I created a Windows Form class.
In this Form, I placed an OK button and I went into the properties of the button and set the DialogResult to OK.
Now, I am calling this Dialog (Window Form) from the MainWindow.xaml.cs:

                        dres = form.ShowDialog();
                        if (dres != DialogResult.OK) return;

The compiler is complaining:

Error    3    'System.Nullable<bool>' does not contain a definition for 'OK' and no extension method 'OK' accepting a first argument of type 'System.Nullable<bool>' could be found (are you missing a using directive or an assembly reference?)

[Plater]

Sounds like ShowDialog() in that context returns a type "bool?" (nullable bool)

[ThatThatGuy]

@complete
Form.ShowDialog() here returns nullable bool...

and not a value supported by the enum DialogResult..

Dialog Result objects can be returned only by SaveFileDialog,FolderBrowserDialog,OpenFileDialog. . etc

It doesn't apply on custom made dialogs..

[Plater]

Well in regular windows programing, anything that inherits from the Form object (so all of your custom forms) supports the ShowDialog() function with a return value of type DialogResult. Why it is NOT done that way in WPF is not something I know, but it seemed perfectly resonable it would work.