I want to customize the following Listbox-display property of border with CornerRadius=5..can anyone help me to achieve it without changing the existing datatemplate code in
If you want the Border within the ListBoxItems to have another CornerRadius value, you can either re-template ListBoxItem where the Border is defined, or set it implicitly in the ItemContainerStyle Resources
<ListBox ...>
<ListBox.ItemContainerStyle>
<Style TargetType="ListBoxItem">
<Style.Resources>
<Style TargetType="Border">
<Setter Property="CornerRadius" Value="5"/>
</Style>
</Style.Resources>
</Style>
</ListBox.ItemContainerStyle>
<!--...-->
</ListBox>
Edit: If you want to set CornerRadius for the ListBox, you can do the same but in Resources instead
<ListBox ...>
<ListBox.Resources>
<Style TargetType="Border">
<Setter Property="CornerRadius" Value="10"/>
</Style>
</ListBox.Resources>
<!--...-->
</ListBox>