What are the defaults for Binding.Mode=Default for WPF controls?

In WPF Binding.Mode, when selecting Default, it depends in the property being binded.

I am looking for some list or some convention or any information for the defaults for the various controls.
I mean, what properties are TwoWay by default and so on. Any links, ideas, thoughts and even rants are welcommed!

> Similar to UpdateSourceTrigger, the > default value for the Mode property > varies for each property. > User-editable properties such as > TextBox.Text, ComboBox.Text, > MenuItem.IsChecked, etc, have TwoWay > as their default Mode value. To figure > out if the default is TwoWay, look at > the Dependency Property Information > section of the property. If it says > BindsTwoWayByDefault is set to true, > then the default Mode value of the > property is TwoWay. To do it > programmatically, get the property > metadata of the property by calling > GetMetadata and then check the boolean > value of the BindsTwoWayByDefault > property.

Source: https://web.archive.org/web/20100209025938/http://blogs.msdn.com/wpfsdk/archive/2006/10/19/wpf-basic-data-binding-faq.aspx

The safest way would be to always be explicit what kind of binding mode you want from a binding.

Here's a way to find the Default mode supported by a DP -

> .NET Reflector is your friend. With reflector, search for TextBox and > look at the source for the static constructor (.cctor()). Here, you > will be able to find the code used for registering the TextProperty > DP: > > > TextProperty = DependencyProperty.Register > ( > "Text", > typeof(string), > typeof(TextBox), > new FrameworkPropertyMetadata > ( > string.Empty, > FrameworkPropertyMetadataOptions.Journal | > FrameworkPropertyMetadataOptions.BindsTwoWayByDefault, > new PropertyChangedCallback(TextBox.OnTextPropertyChanged), > new CoerceValueCallback(TextBox.CoerceText), > true, > UpdateSourceTrigger.LostFocus > ) > ); > > Notice that a parameter is passed to the Register method indicating > the default Binding Mode: > FrameworkPropertyMetadataOptions.BindsTwoWayByDefault. If you use > reflector to look at the registration for TextBlock’s Text DP, you > will see that no such value is passed, in which case we assume the > binding is one way by default.

Taken from Bea Stollnitz's post : How can I update an explicit binding within a template?

Although having some kind of list of important DP's would be very helpful.

Was looking for a list as well, mostly to find out which bindings could be set to one-way to improve performance. The following functions can help you find which controls use two-way binding by default:

public IList<DependencyProperty> GetAttachedProperties(DependencyObject obj)
{
    var result = new List<DependencyProperty>();
    foreach (PropertyDescriptor pd in TypeDescriptor.GetProperties(obj, new Attribute[] { new PropertyFilterAttribute(PropertyFilterOptions.Valid) }))
    {
        var dpd = DependencyPropertyDescriptor.FromProperty(pd);
        if (dpd != null)
        {
            result.Add(dpd.DependencyProperty);
        }
    }
    return result;
}

public bool IsBindsTwoWayByDefault(DependencyObject obj, DependencyProperty property)
{
    var metadata = property.GetMetadata(obj) as FrameworkPropertyMetadata;
    if (metadata != null)
    {
        return metadata.BindsTwoWayByDefault;
    }
    return false;
}

Using a print function, gives us a list:

var objList = new List<DependencyObject> { new TextBox(), new TextBlock(), new Label(), new ComboBox(), new Button() };
foreach (var obj in objList)
{
    var props = GetAttachedProperties(obj);
    foreach (var prop in props)
    {
        if(IsBindsTwoWayByDefault(obj, prop))
            Debug.WriteLine($"{obj} : {prop.OwnerType}:{prop.Name}");
    }
}

Sample result (control properties with two-way binding as default)

System.Windows.Controls.TextBox : System.Windows.Controls.TextBox:Text
System.Windows.Controls.TextBox : System.Windows.Controls.TextSearch:Text
System.Windows.Controls.TextBlock : System.Windows.Controls.TextSearch:Text
System.Windows.Controls.Label : System.Windows.Controls.TextSearch:Text
System.Windows.Controls.ComboBox Items.Count:0 : System.Windows.Controls.ComboBox:IsDropDownOpen
System.Windows.Controls.ComboBox Items.Count:0 : System.Windows.Controls.ComboBox:Text
System.Windows.Controls.ComboBox Items.Count:0 : System.Windows.Controls.Primitives.Selector:SelectedIndex
System.Windows.Controls.ComboBox Items.Count:0 : System.Windows.Controls.Primitives.Selector:SelectedItem
System.Windows.Controls.ComboBox Items.Count:0 : System.Windows.Controls.Primitives.Selector:SelectedValue
System.Windows.Controls.ComboBox Items.Count:0 : System.Windows.Controls.TextSearch:Text
System.Windows.Controls.Button : System.Windows.Controls.TextSearch:Text

Interestingly, most controls have a TextSearch property which has two-way binding.