> I'll have to look into FocusScopes, though I don't see any issues there (I
> might be overlooking something...).

> Josh

> On Mon, Mar 15, 2010 at 6:31 AM, Peter O'Hanlon <pete.ohan...@gmail.com>wrote:

>> The only thing that stands out to me is that this is going to have to be
>> applied in a lot of places in a typical LOB application, so that might be a
>> little bit tedious. What effects do FocusScope's have here? I'll need to
>> play around with this a bit just to make sure there aren't any edge cases
>> that occur (I'm primarily thinking of cases where loss of focus to a
>> menu/toolbar triggers the validation but the parent FocusScope has changed
>> from the textbox).

>> Pete

>>   On Mon, Mar 15, 2010 at 2:24 PM, Josh Smith <flappleja...@gmail.com>wrote:

>>> Thanks.  Any pitfalls or gotchas sticking their heads out?

>>> On Mon, Mar 15, 2010 at 1:03 AM, Peter O'Hanlon <pete.ohan...@gmail.com>wrote:

>>>> I like it - I know that it feels "dirty", but it's actually pretty darn
>>>> cool.

>>>>  On Mon, Mar 15, 2010 at 3:54 AM, Josh Smith <flappleja...@gmail.com>wrote:

>>>>> A while back Dr. WPF graced us with his clever hack of controlling
>>>>> input focus from VM objects.  It involved hijacking the VM's IDataErrorInfo
>>>>> implementation, and doing all sorts of evil-genius stuff to make the input
>>>>> caret move to the correct element.  Today while I was *trying* to read
>>>>> a great novel, I couldn't stop thinking about another way to control input
>>>>> focus from a viewmodel object.

>>>>> I put the novel down and did a quick spike of the idea.  The source
>>>>> code is attached (rename it from .DOC to .ZIP since gmail is terrified of
>>>>> ZIP files for some reason).  Here's the general idea...

>>>>> Implement this interface on your VM class:

>>>>>  /// <summary>
>>>>> /// Implemented by a ViewModel that needs to control
>>>>> /// where input focus is in a View.
>>>>> /// </summary>
>>>>> public interface IFocusController
>>>>> {
>>>>>     /// <summary>
>>>>>     /// Raised when the input focus should move to
>>>>>     /// a control whose 'active' dependency property
>>>>>     /// is bound to the specified property.
>>>>>     /// </summary>
>>>>>     event EventHandler<MoveFocusEventArgs> MoveFocus;
>>>>> }

>>>>> Next, in your VM object (which might implement IDataErrorInfo), do
>>>>> something like this to support a Save button:

>>>>>  public ICommand SaveCommand
>>>>> {
>>>>>     get { return new RelayCommand(this.Save); }
>>>>> }

>>>>> void Save()
>>>>> {
>>>>>     if (this.HasError)
>>>>>     {
>>>>>         // The Error property knows which property is invalid.
>>>>>         this.RaiseMoveFocus(this.Error);
>>>>>     }
>>>>>     else
>>>>>     {
>>>>>         // Save to database...
>>>>>         System.Windows.MessageBox.Show("Saved");
>>>>>     }
>>>>> }

>>>>> bool HasError
>>>>> {
>>>>>     get { return _validatedProperties.Any(prop =>
>>>>> !String.IsNullOrEmpty(this[prop])); }
>>>>> }

>>>>>  public event EventHandler<MoveFocusEventArgs> MoveFocus;

>>>>> void RaiseMoveFocus(string focusedProperty)
>>>>> {
>>>>>     var handler = this.MoveFocus;
>>>>>     if (handler != null)
>>>>>     {
>>>>>         handler(this, new MoveFocusEventArgs(focusedProperty));
>>>>>     }
>>>>> }

>>>>> Lastly, in your View, use my terribly(?) named attached property to
>>>>> specify which DP on your elements is bound to the validated property of the
>>>>> VM, for example:

>>>>>  <TextBox
>>>>>     Text="{Binding Path=FirstName, ValidatesOnDataErrors=True}"
>>>>>     *local:FocusControl.ValidatedProperty="TextBox.Text"*
>>>>>     />

>>>>> I'm not sure that I like this approach yet.  It's a pretty important
>>>>> topic, so I thought I'd share this out amongst the Disciples for feedback.

>>>>> Thanks,
>>>>> Josh

>>>> --
>>>> Peter O'Hanlon

>> --
>> Peter O'Hanlon