Well, I can't answer for Jordan but I'll try to illustrate.
While using the Model-View-ViewModel pattern you have all your UI state
and behavior in a separate class. This class is normally set as the data
context on your View (XAML page), and you bind everything against this
class. Even things like "IsSaveEnabled" to enable the save button.

The View communicates back to the ViewModel by commands. The benefit is that
you don't have any "btnSave_Click" event handler in your codebehind. Instead
your ViewModel waits for that Command to trigger, and then do the work.

The benefit of designing your application using these patterns is that you
can build quite big applications with (almost) no code-behind. This makes
your app easier to test, more maintainable, and easier to work with for a
designer using Blend. So what is the problem? The problem is that there is
no declarative(XAML) way of triggering animations when thing happens. So if
you want to start a storyboard then the ViewModel IsBussy property is true,
you will have to write this code by hand.

Typically that would involve listening to a PropertyChanged event in the
codebehind of the form, and when the ViewModel IsBussy changes to true, then
start the storyboard, when it changes to false, then stop it. This isn't the
end of the world, but when we're so close to achieving no-code behind it
would be nice to go all the way. Also, doing this forces your designer to
have a stroyboard with that exact name (say ShowProgressanimation) present,
so you as the developer ends up "owning" part of the user experience. If the
designer accidentally deletes the storyboard the app will fail at runtime,
or perhaps not even compile. The less named elements in your XAML file the
better.

- Jonas

On Fri, Sep 19, 2008 at 1:12 PM, Barry Beattie <[EMAIL PROTECTED]>wrote:

> > It's a PITA to make apps with all the bells and whistles in XAML then
> have
> > to break M-V-VM to "finish" it off.
>
> got an example to show what you mean? (just curious/wanting to learn)
>
>
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