>>Even with that fix the method I used in my code to set the property will still set it to false and since that's the same call xaml uses, so will the xaml. The only work around I know for that is to make ContentIsLocked readonly, but then you won't be able to set it from xaml :-(
>
>AFAICS the only place to trap and handle this is in the Coerce callback. But I was still confused as to the result of returning DependencyProperty.UnSetValue from this. I now see that this just leaves the old value in place rather than being the equivalent of .ClearValue() which is what I need. But so far I don't see how I can achieve the latter within the callback method .......
>Best,
>Viv

Unfortunately... I wasn't able to find a good solution for this.

I may try some more tonight, but so far no joy.