>>>I think I'm breaking your code. Don't have more time to play with it right now, but here's what I have:
>>>
>>>XAML:

>>><Window x:Class="WpfPropertyInheritance.Window1"
>>>    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
>>>    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
>>>    xmlns:loc="clr-namespace:WpfPropertyInheritance"
>>>    Title="Window1" Height="300" Width="300">
>>>    <StackPanel>
>>>    <Button Height="23" Name="button1" Width="75" Click="button1_Click">Button</Button>
>>>    <Button Height="23" Name="button2" Width="75" Click="button2_Click">Button</Button>
>>>    <loc:ShapeCanvas3 x:Name="scTest" Height="172">
>>>      <StackPanel Canvas.Left="46" Canvas.Top="38" Height="100" Name="spnlTest" Width="200" >
>>>        <Rectangle Height="100" Name="rectangle1" Stroke="Black" Width="200" Fill="Azure" />
>>>      </StackPanel>
>>>    </loc:ShapeCanvas3>
>>>  </StackPanel>
>>></Window>
>>>

>>>
>>>C#:

using System.Windows;
>>>using System.Windows.Controls;
>>>using System.Diagnostics;
>>>
>>>namespace WpfPropertyInheritance
>>>  {
>>>  /// <summary>
>>>  /// Interaction logic for Window1.xaml
>>>  /// </summary>
>>>  public partial class Window1 : Window
>>>    {
>>>    public Window1()
>>>      {
>>>      InitializeComponent();
>>>      }
>>>
>>>    private void button1_Click(object sender, RoutedEventArgs e)
>>>      {
>>>      Debug.WriteLine("A1 Starting Value: " + scTest.ContentIsLocked.ToString());
>>>      scTest.ContentIsLocked = true;
>>>      Debug.WriteLine("A2 Set Canvas True: " + scTest.ContentIsLocked.ToString());
>>>      scTest.ContentIsLocked = true;
>>>      Debug.WriteLine("A3 Set Canvas True Again: " + scTest.ContentIsLocked.ToString());
>>>      scTest.ContentIsLocked = false;
>>>      Debug.WriteLine("A4 Set Canvas False: " + scTest.ContentIsLocked.ToString());
>>>      }
>>>
>>>    private void button2_Click(object sender, RoutedEventArgs e)
>>>      {
>>>      Debug.WriteLine("B2 Starting Values: " + scTest.ContentIsLocked.ToString()+ ":" + rectangle1.GetValue(ShapeCanvas3.ContentIsLockedProperty).ToString());
>>>      scTest.ContentIsLocked = true;
>>>      Debug.WriteLine("B2 Set Canvas True: " + scTest.ContentIsLocked.ToString() + ":" + rectangle1.GetValue(ShapeCanvas3.ContentIsLockedProperty).ToString());
>>>      rectangle1.SetValue(ShapeCanvas3.ContentIsLockedProperty, false);
>>>      Debug.WriteLine("B2 Set Rect False: " + scTest.ContentIsLocked.ToString() + ":" + rectangle1.GetValue(ShapeCanvas3.ContentIsLockedProperty).ToString());
>>>      }
>>>    }
>>>
>>>  public class ShapeCanvas3 : Canvas
>>>    {
>>>    public static DependencyProperty ContentIsLockedProperty;
>>>
>>>    static ShapeCanvas3()
>>>      {
>>>      FrameworkPropertyMetadata p = new FrameworkPropertyMetadata(
>>>        new PropertyChangedCallback(OnContentIsLockedChanged), 
>>>        new CoerceValueCallback(CoerceIsLocked)
>>>        );
>>>      p.Inherits = true;
>>>      ContentIsLockedProperty = DependencyProperty.RegisterAttached("ContentIsLocked", typeof(bool), typeof(ShapeCanvas3), p);
>>>      }
>>>
>>>    public bool ContentIsLocked
>>>      {
>>>      set {
>>>          Debug.WriteLine("SetVal: " + value.ToString());
>>>          if (value)
>>>            SetValue(ContentIsLockedProperty, value);
>>>          else
>>>            this.ClearValue(ContentIsLockedProperty);
>>>          }
>>>      get { return (bool)GetValue(ContentIsLockedProperty); }
>>>      }
>>>
>>>    private static void OnContentIsLockedChanged(DependencyObject obj, DependencyPropertyChangedEventArgs e)
>>>      {
>>>      }
>>>
>>>    private static object CoerceIsLocked(DependencyObject d, object value)
>>>      {
>>>      if (d.ReadLocalValue(ContentIsLockedProperty) == DependencyProperty.UnsetValue)
>>>        {
>>>        Debug.WriteLine("Coerce 1: "+d.ToString()+":" + value.ToString());
>>>        return value;
>>>        }
>>>      bool b = (bool)value;
>>>      if (b)
>>>        {
>>>        Debug.WriteLine("Coerce 2: " + b.ToString());
>>>        return b;
>>>        }
>>>      else
>>>        {
>>>        Debug.WriteLine("Coerce 3: UnsetValue");
>>>        return DependencyProperty.UnsetValue;
>>>        }
>>>      }
>>>    
>>>    }  
>>>  }

>>>
>>>Here is the debug output on the second button:
>>>
>>>

>>>B2 Starting Values: False:False
>>>SetVal: True  
>>>Coerce 1: WpfPropertyInheritance.ShapeCanvas3:True
>>>Coerce 1: System.Windows.Controls.StackPanel:True
>>>Coerce 1: System.Windows.Shapes.Rectangle:True
>>>B2 Set Canvas True: True:True
>>>Coerce 1: System.Windows.Shapes.Rectangle:False
>>>B2 Set Rect False: True:False
>>>

>>>
>>>B2 Set Rect False: True:False = Canvas is locked, but child was able to be unlocked.
>>>
>>>Am I missing something?
>>
>>Hi,
>>I'm dragged back into VFP/ASP.NET for a couple of days so I can't try your version at the mo.....
>>I'll get back to you ASAP,
>>Viv

>I may have a solution to all of this, but I need to understand your usage a bit better. So let's see if I have this right.

Hi,
Just quick answers I'm afraid:

>ShapeCanvas3 is the root object.
Not neccessarily, but for the sake of this exercise - yes.

>If it is locked, all children are locked and no child can be unlocked.
Yes

>That's easy I have that coded.
>Now here's where the questions come in. Some options will be harder to code then others.
>Will ShapeCanvas3's children also have children that also need to be locked and unlocked?
Yes. With, from a logic POV, potentially unlimited nesting.

>And if ShapeCanvas3 becomes unlocked what should the behavior be:
>A. All children become unlocked.
>B. All children revert to their previously requested lock/unlock state.
>C. All children stay locked until they are explicitly unlocked.
If a child is explicitly locked it stays locked. If not it inherits from it's parent element so I think that means B.
(There should never be an explictly unlocked status)

>A I have coded, B I know how to code, C is going to be tricky, I think we will have to walk the tree in order to clear any previously unlocked DP off the children.

But if all children stayed locked unless explicitly unlocked then I wouldn't need property inheritance in the first place :-}

>I will probably have more questions based on your answer.
Fire away (g) - but, AFAICS, my current solution is working (well, I haven't been able to break it yet - i.e. end up with a element where the property is explicitly false).

Oh - and note that when using an attached property the same logic applies to nested elements other than ShapeCanvas3.
Best,
Viv