Question

I’m writing a Windows shell extension in C# using EZShellExtensions.NET.

I contribute a context menu that shows dialogs.

Suppose that I show an Explorer window (A). Then I use the context menu to show non modal window (B).

In Windows XP and Windows Vista, when I close A, B is closed (I want this behavior). However, in Windows 7, when I close A, B is not closed but it doesn’t respond to events. My questions are:

• Do you know why Windows 7 manage the showed form as a child form?
• Is there a way to maintain the message loop if I close A?

EDIT: If I set A as owner of B, when I close A, B is also closed. But it creates a new issue. B is always over A.

Answer 1

Finally I have implemented it in the following way. The dialog is shown using ShowDialog() but is launched (and created in a thread). ShowDialog() implements its own message loop, so as the form is launched in a thread, the main form respond to events, and also you can close the main form and the child form still respond to events. This is very useful for a ShellExtension application.

Remember dispose all on your form, in order to free the thread, and also the shell extension thread (each shell extension window and childs are executed in a thread).

The following code fixed my issue:

    protected virtual void SetupViewControl()
    {
        ThreadPool.QueueUserWorkItem(new WaitCallback(DoSetupViewControl));

        while (!mViewControlCreated)
        {
            // wait for view control created
            Thread.Sleep(100);
        }
    }

    private bool mViewControlCreated = false;

    protected virtual void DoSetupViewControl(object state)
    {
        mViewControl = ViewControlFactory.CreateViewControl();

        mViewControl.Dock = DockStyle.Fill;
        mViewControl.Initialize();

        this.Controls.Clear();
        this.Controls.Add(mViewControl);

        IntPtr wHnd = GetActiveWindow();
        IWin32Window owner = GetOwner(wHnd);

        mViewControlCreated = true;

        ShowDialog(owner);

        this.Dispose();
    }

    private IWin32Window GetOwner(IntPtr wHnd)
    {
        if (wHnd == IntPtr.Zero) return null;

        return new WindowWrapper(wHnd);
    }

    [DllImport("user32.dll", CharSet = CharSet.Auto, ExactSpelling = true)]
    private static extern IntPtr GetActiveWindow();

    private class WindowWrapper : IWin32Window
    {
        private IntPtr mHwnd;

        public WindowWrapper(IntPtr handle)
        {
            mHwnd = handle;
        }

        public IntPtr Handle
        {
            get { return mHwnd; }
        }
    }