I am displaying a Form from one process by passing the Show method a window handle from another process. I only want this new Form to display above the passed Form, like a MessageBox.

However, this newly launched Form appears above other application windows, despite:

• Setting Process.WindowStyle.Hidden to the Form-displaying process
• Overriding the ShowWithoutActivation and CreateParams properties of the Form.
• Making sure Form.TopMost is not true

I have checked that the window handle is valid from the second process. Focus is not stolen, however.

Process A:
Pass (Form) window handle to a new Process B via the command line

Process B:
Display a new Form using Form.Show(anotherProcessWindowHandle)