feat: introducing background and foreground setting for loading container.

src/Ursa.Themes.Semi/Controls/Loading.axaml

@@ -93,6 +93,8 @@
 
     <ControlTheme x:Key="{x:Type u:LoadingContainer}" TargetType="u:LoadingContainer">
         <Setter Property="HorizontalContentAlignment" Value="Center" />
+        <Setter Property="MessageForeground" Value="{DynamicResource TextBlockDefaultForeground}"/>
+        <Setter Property="Background" Value="{DynamicResource LoadingMaskBackground}" />
         <Setter Property="VerticalContentAlignment" Value="Center" />
         <Setter Property="Indicator">
             <Template>
@@ -109,6 +111,8 @@
                         Content="{TemplateBinding Content}"
                         ContentTemplate="{TemplateBinding ContentTemplate}" />
                     <u:Loading
+                        Background="{TemplateBinding Background}"
+                        Foreground="{TemplateBinding MessageForeground}"
                         Content="{TemplateBinding LoadingMessage}"
                         ContentTemplate="{TemplateBinding LoadingMessageTemplate}"
                         Indicator="{TemplateBinding Indicator}"

src/Ursa/Controls/Loading/LoadingContainer.cs

@@ -2,6 +2,7 @@ using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Controls.Metadata;
 using Avalonia.Controls.Templates;
+using Avalonia.Media;
 
 namespace Ursa.Controls;
 
@@ -28,6 +29,15 @@ public class LoadingContainer: ContentControl
         set => SetValue(LoadingMessageProperty, value);
     }
 
+    public static readonly StyledProperty<IBrush?> MessageForegroundProperty = AvaloniaProperty.Register<LoadingContainer, IBrush?>(
+        nameof(MessageForeground));
+
+    public IBrush? MessageForeground
+    {
+        get => GetValue(MessageForegroundProperty);
+        set => SetValue(MessageForegroundProperty, value);
+    }
+
     public static readonly StyledProperty<IDataTemplate> LoadingMessageTemplateProperty = AvaloniaProperty.Register<LoadingContainer, IDataTemplate>(
         nameof(LoadingMessageTemplate));