modified some styles

src/Shared/HandyControl_Shared/Themes/Styles/RichTextBox.xaml

@@ -2,13 +2,17 @@
                     xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                     xmlns:controls="clr-namespace:HandyControl.Controls">
 
+    <ResourceDictionary.MergedDictionaries>
+        <ResourceDictionary Source="../Basic/Sizes.xaml"/>
+    </ResourceDictionary.MergedDictionaries>
+
     <Style x:Key="TextBoxBaseBaseStyle" TargetType="TextBoxBase">
         <Setter Property="Background" Value="{DynamicResource RegionBrush}"/>
         <Setter Property="BorderBrush" Value="{DynamicResource BorderBrush}"/>
         <Setter Property="Foreground" Value="{DynamicResource PrimaryTextBrush}"/>
         <Setter Property="BorderThickness" Value="1"/>
         <Setter Property="CaretBrush" Value="{DynamicResource PrimaryTextBrush}"/>
-        <Setter Property="controls:BorderElement.CornerRadius" Value="4"/>
+        <Setter Property="controls:BorderElement.CornerRadius" Value="{StaticResource DefaultCornerRadius}"/>
         <Setter Property="KeyboardNavigation.TabNavigation" Value="None"/>
         <Setter Property="HorizontalContentAlignment" Value="Left"/>
         <Setter Property="FocusVisualStyle" Value="{x:Null}"/>