Question

I want create something that looks like the MSN Messenger chat forms.

I am looking to create the following behavior:

1. You double-click a user on your user list
2. Messenger opens a form for that user, with your previous chat log with that user
3. You go back to your user list and double-click that user again
4. Messenger brings the previously opened form back into focus without creating another form

How can I recreate this behavior in C# WinForms

Answer 1

    Dictionary<Guid, Form> dic = new Dictionary<Guid, Form>();
    public Form ShowForm(Guid userId)
    {
        Form form;
        if (!dic.TryGetValue(userId, out form))
        {
            form = new Form();
            dic.Add(userId, form);
        }
        return form;
    }