Question

i search the web for TextBox with rounded corners and find a xaml code like below:

 <Style TargetType="{x:Type my1:CustomTextBox}">
            <Setter Property="HorizontalContentAlignment" Value="Center"/>
            <Setter Property="Template">
                <Setter.Value>
                    <ControlTemplate >
                        <Border Background="{TemplateBinding Background}" x:Name="Bd" 
BorderThickness="2" CornerRadius="5" BorderBrush="#FFF9EAB6">
                            ***<ScrollViewer x:Name="PART_ContentHost" />***
                        </Border>
                        <ControlTemplate.Triggers>
                            <Trigger Property="IsMouseOver" Value="True">
                                <Setter TargetName="Bd" Property="BorderBrush" Value="#FFC7B0B0"/>
                            </Trigger>
                            <Trigger Property="IsKeyboardFocused" Value="True">
                                <Setter TargetName="Bd" Property="BorderBrush" Value="#FFC7B0B0"/>
                                <Setter Property="Foreground" Value="Black"/>
                            </Trigger>
                            <Trigger Property="IsKeyboardFocused" Value="False">
                                <Setter Property="Foreground" Value="#FFC7B0B0"/>
                            </Trigger>
                            <Trigger Property="Width" Value="Auto">
                                <Setter Property="MinWidth" Value="120"/>
                            </Trigger>
                            <Trigger Property="Height" Value="Auto">
                                <Setter Property="MinHeight" Value="27"/>
                            </Trigger>
                        </ControlTemplate.Triggers>
                    </ControlTemplate>

                </Setter.Value>
            </Setter>
        </Style>

i want to find out what is

<ScrollViewer x:Name="PART_ContentHost" />

in detail and why not properly work my template if delete this line from it,
please tell me completely in detail.

thanks alot.

Answer 1

The part named “PART_ContentHost” contains the control core, this is the textbox itself, besides the adornments. The textbox’s code behind will look for it, so if you rename of delete, the control wont work.
In this case, the content is scrollable (as a textbox can scroll text horizontally and vertically).