[DevExpress] Add Fluent styles for TreeDataGrid

Author: apman

samples/SampleApp/App.axaml

@@ -5,20 +5,14 @@
         <Styles x:Key="LinuxYaruStyles">
             <StyleInclude Source="avares://Devolutions.AvaloniaTheme.Linux/LinuxTheme.axaml" />
             <StyleInclude Source="/Styles.axaml" />
-            <!-- TODO: move into themes -->
-            <StyleInclude Source="avares://Avalonia.Controls.TreeDataGrid/Themes/Fluent.axaml" />
         </Styles>
         <Styles x:Key="DevExpressStyles">
             <StyleInclude Source="avares://Devolutions.AvaloniaTheme.DevExpress/DevExpressTheme.axaml" />
             <StyleInclude Source="/Styles.axaml" />
-            <!-- TODO: move into themes -->
-            <StyleInclude Source="avares://Avalonia.Controls.TreeDataGrid/Themes/Fluent.axaml" />
         </Styles>
         <Styles x:Key="MacOsStyles">
             <StyleInclude Source="avares://Devolutions.AvaloniaTheme.MacOS/MacOSTheme.axaml" />
             <StyleInclude Source="/Styles.axaml" />
-            <!-- TODO: move into themes -->
-            <StyleInclude Source="avares://Avalonia.Controls.TreeDataGrid/Themes/Fluent.axaml" />
         </Styles>
     </Application.Resources>
 
@@ -29,7 +23,5 @@
         <StyleInclude Source="avares://Devolutions.AvaloniaTheme.DevExpress/DevExpressTheme.axaml" />
         <!-- <StyleInclude Source="avares://Devolutions.AvaloniaTheme.Linux/LinuxTheme.axaml" /> -->
         <StyleInclude Source="/Styles.axaml" />
-        <!-- TODO: move into themes -->
-        <StyleInclude Source="avares://Avalonia.Controls.TreeDataGrid/Themes/Fluent.axaml" />
     </Application.Styles>
 </Application>

src/Devolutions.AvaloniaTheme.DevExpress/Accents/Styles.axaml

@@ -38,4 +38,13 @@
   <Style Selector="DataGridRow:nth-child(even)">
     <Setter Property="Background" Value="{DynamicResource DataGridRowAlternatingBackgroundBrush}" />
   </Style>
+  
+  <Style Selector=":is(TreeDataGridCell)">
+    <Setter Property="Background" Value="Transparent" />
+    <Setter Property="MinHeight" Value="25" />
+  </Style>
+
+  <Style Selector=":is(TreeDataGridCell):selected">
+    <Setter Property="Background" Value="{DynamicResource TreeDataGridSelectedCellBackgroundBrush}" />
+  </Style>
 </Styles>