>>>>Hi,
>>>>I've built a bool DependencyProperty (with the standard property wrapper) that implements inheritance.
>>>>If I set the property wrapper to 'true' I want it to set this on the DependencyProperty
>>>>But when I set it to 'false' I want to execute the .ClearValue() method instead.
>>>>I know I can't do this in the wrapper, or in the ValidateValueCallback - but can I do it in the CoerceValueCallback?
>>>>Or is there another way (maybe a wrapper for the wrapper?)
>>>>
>>>>Best,
>>>>Viv
>>>
>>>I've never actually used those functions... But so far in WPF when I can't do something like that from where I am, I can usually do it with a delegate.
>>>
>>>If that won't work, maybe you could post a little code that shows what you are trying to do.
>>Hi,
>>For now I've just used the wrapper to control this:

public class ShapeCanvas3: Canvas
>>       public static DependencyProperty ContentIsLockedProperty;
>>
>>        static ShapeCanvas3()
>>        {
>>            FrameworkPropertyMetadata p = new FrameworkPropertyMetadata();
>>            p.Inherits = true;
>>            ContentIsLockedProperty = DependencyProperty.Register("ContentIsLocked", typeof(bool), typeof(ShapeCanvas3), p);
>>        }
>>
>>        public bool ContentIsLocked
>>        {
>>            set
>>            {
>>                if (value)
>>                    SetValue(ContentIsLockedProperty, value);
>>                else
>>                    this.ClearValue(ContentIsLockedProperty);
>>            }
>>            get { return (bool)GetValue(ContentIsLockedProperty); }
>>        }
>>}

This works OK for me at the moment but ideally I'd like to prevent the DependencyProperty being set to false in XAML etc. I'll experiment with trying to do something in either the Valid or CoerceValue callback but, from the docs, it doesn't seem doable....
>>Regards,
>>Viv
>
>Ok... next silly question. Why do want to clear it?
>
>I think I'm not fully getting your code here, cause when I look at it, it looks like you are defaulting the value to true. So when you clear the control by setting it to false, wouldn't it still return true?
>
>I'm thinking you might have wanted to make it read only, but I'm not sure what you are trying to do.

If true is passed in then it sets the property to true. When false is passed in I execute the ClearValue() so the value of the dependency property will be the inherited value. So the only two states the dependency property can have are either 'Locked' or the inherited state - it cannot be false (except via inheritance). The only flaw with this is that it is still possible to set the dependency property to false by methods other than via the wrapper property (for example by calling SetValue() directly). I was hoping to close these loopholes in one of the callbacks.
Regards,
Viv