ux: add brush for Window border on Linux

Author: love-linger

README.md

@@ -97,6 +97,7 @@ This app supports open repository in external tools listed in the table below.
 | Key | Description |
 | --- | --- |
 | Color.Window | Window background color |
+| Color.WindowBorder | Window border color. Only used on Linux. |
 | Color.TitleBar | Title bar background color |
 | Color.ToolBar | Tool bar background color |
 | Color.Popup | Popup panel background color |

src/Resources/Styles.axaml

@@ -118,7 +118,7 @@
           <Grid Margin="{TemplateBinding Padding}" Effect="drop-shadow(0 0 12 #A0000000)">
             <Border x:Name="PART_ContentRoot"
                     Background="{DynamicResource Brush.Window}"
-                    BorderBrush="{DynamicResource Brush.Border0}"
+                    BorderBrush="{DynamicResource Brush.WindowBorder}"
                     BorderThickness="1"
                     CornerRadius="8">
               <VisualLayerManager>

src/Resources/Themes.axaml

@@ -6,6 +6,7 @@
       <Color x:Key="Color.MacOS.Minimize">#FFFFBE2F</Color>
       <Color x:Key="Color.MacOS.Maximize">#FF29c941</Color>
       <Color x:Key="Color.Window">#FFF0F5F9</Color>
+      <Color x:Key="Color.WindowBorder">#FFAFAFAF</Color>
       <Color x:Key="Color.TitleBar">#FFCFDEEA</Color>
       <Color x:Key="Color.ToolBar">#FFF0F5F9</Color>
       <Color x:Key="Color.Popup">#FFF8F8F8</Color>
@@ -36,6 +37,7 @@
       <Color x:Key="Color.MacOS.Minimize">#FFFCBB2D</Color>
       <Color x:Key="Color.MacOS.Maximize">#FF25C53C</Color>
       <Color x:Key="Color.Window">#FF252525</Color>
+      <Color x:Key="Color.WindowBorder">#FF444444</Color>
       <Color x:Key="Color.TitleBar">#FF1F1F1F</Color>
       <Color x:Key="Color.ToolBar">#FF2C2C2C</Color>
       <Color x:Key="Color.Popup">#FF2B2B2B</Color>
@@ -66,6 +68,7 @@
   <SolidColorBrush x:Key="Brush.MacOS.Minimize" Color="{DynamicResource Color.MacOS.Minimize}"/>
   <SolidColorBrush x:Key="Brush.MacOS.Maximize" Color="{DynamicResource Color.MacOS.Maximize}"/>
   <SolidColorBrush x:Key="Brush.Window" Color="{DynamicResource Color.Window}"/>
+  <SolidColorBrush x:Key="Brush.WindowBorder" Color="{DynamicResource Color.WindowBorder}"/>
   <SolidColorBrush x:Key="Brush.TitleBar" Color="{DynamicResource Color.TitleBar}"/>
   <SolidColorBrush x:Key="Brush.ToolBar" Color="{DynamicResource Color.ToolBar}"/>
   <SolidColorBrush x:Key="Brush.Popup" Color="{DynamicResource Color.Popup}"/>