Invoke a ContextMenu to open

I need to do something like Google Maps does (but in WPF):

• when RightClick on the map I have a ContextMenu.
• when RightDoubleClicking I have the UnZoom action.

So, apparently, this is a little difficult in WPF... After struggling and searching a lot, read people that compains that "we can't predict the future" (I ask myself how does Google predict it), I decided to "wait" SystemInformation.DoubleClickTime and only then display a contextMenu.

Surely, this is not ideal, even human-observable, but I don't know other method.

So, the problem that I have with the following code is (I have a custom Canvas):

ContextMenuEventArgs lastContextMenuEventArgs开发者_JS百科 = null;
bool? lastContextMenuEventArgsHandled = null;

protected override void OnContextMenuOpening(ContextMenuEventArgs e)
{
    lastContextMenuEventArgs = e;
    lastContextMenuEventArgsHandled = e.Handled;

    e.Handled = true;
    //base.OnContextMenuOpening(e);
}

bool rightMouseClickedOnce = false;
protected override void OnPreviewMouseRightButtonUp(MouseButtonEventArgs e)
{
    //base.OnPreviewMouseRightButtonUp(e);

    Console.WriteLine(">>>>>>>>>>> OnPreviewMouseRightButtonUp");
    if (!rightMouseClickedOnce)
    {
        rightMouseClickedOnce = true;
        Thread thread = new Thread(
            new System.Threading.ThreadStart(
                delegate()
                {
                    Thread.Sleep(System.Windows.Forms.SystemInformation.DoubleClickTime);
                    this.Dispatcher.Invoke(
                        System.Windows.Threading.DispatcherPriority.Background,
                        new Action(
                            delegate()
                            {
                                if (rightMouseClickedOnce)
                                {
                                    Console.WriteLine(">>>>>>>>>>> Right Click");
                                    rightMouseClickedOnce = false;
                                    base.OnPreviewMouseRightButtonUp(e);

                                    if (lastContextMenuEventArgsHandled.HasValue)
                                    {
                                        Console.WriteLine(">>>>>>>>>>> lastContextMenuEventArgsHandled");
                                        lastContextMenuEventArgs.Handled = lastContextMenuEventArgsHandled.Value;
                                        base.OnContextMenuOpening(lastContextMenuEventArgs);
                                        lastContextMenuEventArgsHandled = null;
                                    }
                                    //if (this.ContextMenu != null)
                                    //{
                                    //  this.ContextMenu.PlacementTarget = this;
                                    //  this.ContextMenu.IsOpen = true;
                                    //}
                                }
                            }
                    ));
                }
        ));
        thread.Start();
    }
    else if (rightMouseClickedOnce)
    {
        Console.WriteLine(">>>>>>>>>>> Right Double Click");
        rightMouseClickedOnce = false;
        base.OnPreviewMouseRightButtonUp(e);
        this.OnMouseRightDoubleClick(e);
    }

}

Everything works great but a little problem: base.OnContextMenuOpening(lastContextMenuEventArgs); does not seem to work...

I set before

if (this.ContextMenu != null)
{
  this.ContextMenu.PlacementTarget = this;
  this.ContextMenu.IsOpen = true;
}

and that worked, but finally this blocks child contextMenu elements from opening, and open always the parent (canvas) contextMenu.

Can I just invoke the contextMenu event?

---

I don't know much about WPF, but can you show the menu, say, a pixel away from the cursor and see if the user right-clicks again in the same spot and in the system double click time? I've used a similar technique once in a game and it performed nice enough.
A menu "fade in" (optionally, out, too) animation could make it even better.