Not needed for 3.1.2 - Bryan

I've been thinking about this and came up with a solution that doesn't break compatibility with Blend.

Instead of changing the default property to inherit, you can create an attached inherited property that will be in charge of updating the default property:

public static class TouchHelper

{

public static bool GetIsDoubleTapEnabled(UIElement obj)

{

return (bool)obj.GetValue(IsDoubleTapEnabledProperty);

}

public static void SetIsDoubleTapEnabled(UIElement obj, bool value)
{
    obj.SetValue(IsDoubleTapEnabledProperty, value);
}

public static readonly DependencyProperty IsDoubleTapEnabledProperty = DependencyProperty.RegisterAttached(
    "IsDoubleTapEnabled", typeof(bool?), typeof(TouchHelper),
    new FrameworkPropertyMetadata(null, FrameworkPropertyMetadataOptions.Inherits, OnIsDoubleTapEnabledChanged));

private static void OnIsDoubleTapEnabledChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
    if (e.NewValue != null)
    {
        ((UIElement)d).IsDoubleTapEnabled = (bool)e.NewValue;
    }
}
}

Then you can use it in the xaml as you suggested, disabling it for the whole window, and then enabling it only on the controls you need it:

<Window x:Class="UIShell.MainWindow"

xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"

xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"

xmlns:local="clr-namespace:UIShell"

local:TouchHelper.IsDoubleTapEnabled="False" ...>

...

<Button local:TouchHelper.IsDoubleTapEnabled="True"/>

...

<TextBox local:TouchHelper.IsDoubleTapEnabled="True"/>

...

</Window>

This looks like it'll work well. I've added the changes into our application, with one minor change: I changed GetIsDoubleTapEnabled to return "bool?", rather than plain "bool".

I am somewhat concerned about how this would interact with some control setting UIElement.IsDoubleTapEnabled directly: If some control has UIElement.IsDoubleTapEnabled set, and I have TouchHelper.IsDoubleTapEnabled set on MainWindow, then the value from MainWindow might overwrite the value set on the individual control. That said, I'm not sure what to do about it: Calling ReadLocalValue would tell me if it was still default, but don't think it's possible to tell the difference between a non-default because it was set explicitly in that control's XAML, or because TouchHelper set it previously. Perhaps set it up so that TouchHelper would set up a binding from UIElement.IsDoubleTapEnabled to TouchHelper.IsDoubleTapEnabled, but only if there's no local value or another binding set up? I know how to check if there's no local value, or if there's a previously-evaluated binding, but I'm not sure how to tell if there's a binding set up, but hasn't been evaluated yet. But that probably doesn't matter, since we're in control of every element that gets loaded in our application,

The idea of this attached property is that you don't deal with the original one, you shouldn't mix the use of both properties.

That should be fine.

It's only a concern because we do consume a third-party component. I don't have the source to the most recent version of that component, but I do have source to an older version, and that version doesn't touch IsDoubleTapEnabled, so we should be good.

Is it fine to mark this as resolved with the attached property solution?
We feel it is not necessary to change our core implementation and deviate from WPF behavior.