Question

I override borders CornerRadius as a default style in the app.xaml file (like below)

<Application x:Class="BorderCornerProblem.App"
         xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
         StartupUri="MainWindow.xaml">
<Application.Resources>
    <Style TargetType="{x:Type Border}">
        <Setter Property="OverridesDefaultStyle" Value="true"/>
        <Setter Property="CornerRadius" Value="50"/>  
    </Style>
</Application.Resources>
</Application>

and in the MainWindow.xaml file I have

<Window x:Class="BorderCornerProblem.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">       
</Window>

the result is that the window has a black rounded corners.

My question then is how to define a DefaultStyle with CornerRadius set for Border that will not mess with my Window?

Answer 1

You really should not globally style Borders, they are everywhere.

Give the style a key and only reference it where needed.