WinPhone: How to add custom confirmation dialog in OnBackKeyPress

WinPhone: How to add custom confirmation dialog in OnBackKeyPress

I am going to implement custom confirmation dialog in OnBackKeyPress
method. It is easy to do with native message box:
protected override void OnBackKeyPress(CancelEventArgs e)
{
base.OnBackKeyPress(e);
MessageBoxResult result = MessageBox.Show("Text");
if(result==MessageBoxResult.OK)
{
e.Cancel = true;
}
}
It works, but I dislike limitation with two buttons so I am looking for
something else.
I have checked WPtoolkit:
private bool m_cansel = false;
protected override void OnBackKeyPress(CancelEventArgs e)
{
base.OnBackKeyPress(e);
if (!m_cansel)
{
e.Cancel = true;
m_cansel = true;
var messageBox = new CustomMessageBox
{
Title = "Title",
Message = "Message",
RightButtonContent = "aas",
IsLeftButtonEnabled = false,
};
messageBox.Dismissed += (sender, args) =>
{
};
messageBox.Show();
}
}
And Coding4Fun:
private bool m_cansel = false;
protected override void OnBackKeyPress(CancelEventArgs e)
{
base.OnBackKeyPress(e);
if (!m_cansel)
{
e.Cancel = true;
m_cansel = true;
var messageBox = new MessagePrompt
{
Title = "Title",
Message = "Message",
};
messageBox.Completed += (sender, args) =>
{
//throw new NotImplementedException();
};
messageBox.Show();
}
Both looks good, but don't work in OnBackKeyPress method (show and
immediately disappear without any my action).
Moreover, I've tried XNA:
private bool m_cansel = false;
protected override void OnBackKeyPress(CancelEventArgs e)
{
base.OnBackKeyPress(e);
if (!m_cansel)
{
e.Cancel = true;
m_cansel = true;
Guide.BeginShowMessageBox("Version of Windows", "Pick a version of
Windows.",
new List<string> {"Vista", "Seven"}, 0,
MessageBoxIcon.Error,
asyncResult =>
{
int? returned =
Guide.EndShowMessageBox(asyncResult);
}, null);
}
}
It works as I expected (has customs in OnBackKeyPress method), but I don't
sure that using XNA inside Silverlight app is good practice.
So, I am looking a way to use WPtoolkit or Coding4Fun windows inside
OnBackKeyPress method or any explanation about using XNA inside
Silverlight app (any recomendation or info about approval such kind app by
store).