WPF Usercontrol - setting Default-Value of DependencyProperty to Child

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WPF

user-controls

Hi Community,

I've created an usercontrol 'Splitter'.

xaml looks like this:

<UserControl x:Class="DesktopApp.UserControls.Splitter"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" >
    <Border x:Name="oBorder">
            
            <Border.Effect>
                <DropShadowEffect x:Name="oShadow" />
            </Border.Effect>
            
        </Border>
</UserControl>

I want to access some Properties of the oBorder and oShadow-Childs.

For example i want to set the Color-Property of the Child "oBorder" like this:

<uc:Splitter x:Name="oSplitter" SplitterColor="Orange"></uc:Splitter>

where uc is defined as following:

xmlns:uc="clr-namespace:DesktopApp.UserControls"

So I've put a DP called 'SplitterColor' into my usercontrol.

public Brush SplitterColor
        {
            get { return (Brush)GetValue(SplitterColorProperty); }
            set { SetValue(SplitterColorProperty, value); }
        }

I've defined a default value 'Brushes.White'

public static readonly DependencyProperty SplitterColorProperty =
            DependencyProperty.Register("SplitterColor", typeof(Brush), typeof(Splitter), new PropertyMetadata(Brushes.White, OnSplitterColorChanged));

This code changes the Color-Property of by oBorder Child. In this example dNewBackgroundColor will be an Orange brush.

private static void OnSplitterColorChanged(DependencyObject sender, DependencyPropertyChangedEventArgs eventArgs)
        {
            Brush dNewBackgroundColor = eventArgs.NewValue as Brush;
            Splitter oThis;

            if (dNewBackgroundColor != null)
            {
                oThis = sender as Splitter;

                if (oThis != null)
                {
                    //Zuweisung
                    oThis.oBorder.Background = dNewBackgroundColor;
                }
            }
        }

It works fine !

But if i define my control as the following:

<uc:Splitter x:Name="oSplitter" SplitterColor="White"></uc:Splitter>

or

<uc:Splitter x:Name="oSplitter"></uc:Splitter>

my programm will not step into my OnSplitterColorChanged-handler. So my color will not be set to my oBorder Child.

What's the default way to set the default value of my dependency-property to my child ?

Jeff