Add support for selection prompt highlighting

src/Spectre.Console/Widgets/Prompt/MultiSelectionPrompt.cs

@@ -35,6 +35,11 @@ namespace Spectre.Console
         /// </summary>
         public int PageSize { get; set; } = 10;
 
+        /// <summary>
+        /// Gets or sets the highlight style of the selected choice.
+        /// </summary>
+        public Style? HighlightStyle { get; set; }
+
         /// <summary>
         /// Gets or sets a value indicating whether or not
         /// at least one selection is required.
@@ -68,7 +73,7 @@ namespace Spectre.Console
 
             var converter = Converter ?? TypeConverterHelper.ConvertToString;
 
-            var list = new RenderableMultiSelectionList<T>(console, Title, PageSize, Choices, converter);
+            var list = new RenderableMultiSelectionList<T>(console, Title, PageSize, Choices, converter, HighlightStyle);
             using (new RenderHookScope(console, list))
             {
                 console.Cursor.Hide();

src/Spectre.Console/Widgets/Prompt/MultiSelectionPromptExtensions.cs

@@ -103,6 +103,24 @@ namespace Spectre.Console
             return obj;
         }
 
+        /// <summary>
+        /// Sets the highlight style of the selected choice.
+        /// </summary>
+        /// <typeparam name="T">The prompt result type.</typeparam>
+        /// <param name="obj">The prompt.</param>
+        /// <param name="highlightStyle">The highlight style of the selected choice.</param>
+        /// <returns>The same instance so that multiple calls can be chained.</returns>
+        public static MultiSelectionPrompt<T> HighlightStyle<T>(this MultiSelectionPrompt<T> obj, Style highlightStyle)
+        {
+            if (obj is null)
+            {
+                throw new ArgumentNullException(nameof(obj));
+            }
+
+            obj.HighlightStyle = highlightStyle;
+            return obj;
+        }
+
         /// <summary>
         /// Requires no choice to be selected.
         /// </summary>

src/Spectre.Console/Widgets/Prompt/Rendering/RenderableMultiSelectionList.cs

@@ -17,12 +17,12 @@ namespace Spectre.Console
 
         public RenderableMultiSelectionList(
             IAnsiConsole console, string? title, int pageSize,
-            List<T> choices, Func<T, string>? converter)
+            List<T> choices, Func<T, string>? converter, Style? highlightStyle)
             : base(console, pageSize, choices, converter)
         {
             _console = console ?? throw new ArgumentNullException(nameof(console));
             _title = title;
-            _highlightStyle = new Style(foreground: Color.Blue);
+            _highlightStyle = highlightStyle ?? new Style(foreground: Color.Blue);
 
             Selections = new HashSet<int>();
         }

src/Spectre.Console/Widgets/Prompt/Rendering/RenderableSelectionList.cs

@@ -12,12 +12,12 @@ namespace Spectre.Console
         private readonly string? _title;
         private readonly Style _highlightStyle;
 
-        public RenderableSelectionList(IAnsiConsole console, string? title, int requestedPageSize, List<T> choices, Func<T, string>? converter)
+        public RenderableSelectionList(IAnsiConsole console, string? title, int requestedPageSize, List<T> choices, Func<T, string>? converter, Style? highlightStyle)
             : base(console, requestedPageSize, choices, converter)
         {
             _console = console ?? throw new ArgumentNullException(nameof(console));
             _title = title;
-            _highlightStyle = new Style(foreground: Color.Blue);
+            _highlightStyle = highlightStyle ?? new Style(foreground: Color.Blue);
         }
 
         protected override int CalculatePageSize(int requestedPageSize)

src/Spectre.Console/Widgets/Prompt/SelectionPrompt.cs

@@ -34,6 +34,11 @@ namespace Spectre.Console
         /// </summary>
         public int PageSize { get; set; } = 10;
 
+        /// <summary>
+        /// Gets or sets the highlight style of the selected choice.
+        /// </summary>
+        public Style? HighlightStyle { get; set; }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="SelectionPrompt{T}"/> class.
         /// </summary>
@@ -61,7 +66,7 @@ namespace Spectre.Console
 
             var converter = Converter ?? TypeConverterHelper.ConvertToString;
 
-            var list = new RenderableSelectionList<T>(console, Title, PageSize, Choices, converter);
+            var list = new RenderableSelectionList<T>(console, Title, PageSize, Choices, converter, HighlightStyle);
             using (new RenderHookScope(console, list))
             {
                 console.Cursor.Hide();

src/Spectre.Console/Widgets/Prompt/SelectionPromptExtensions.cs

@@ -103,6 +103,24 @@ namespace Spectre.Console
             return obj;
         }
 
+        /// <summary>
+        /// Sets the highlight style of the selected choice.
+        /// </summary>
+        /// <typeparam name="T">The prompt result type.</typeparam>
+        /// <param name="obj">The prompt.</param>
+        /// <param name="highlightStyle">The highlight style of the selected choice.</param>
+        /// <returns>The same instance so that multiple calls can be chained.</returns>
+        public static SelectionPrompt<T> HighlightStyle<T>(this SelectionPrompt<T> obj, Style highlightStyle)
+        {
+            if (obj is null)
+            {
+                throw new ArgumentNullException(nameof(obj));
+            }
+
+            obj.HighlightStyle = highlightStyle;
+            return obj;
+        }
+
         /// <summary>
         /// Sets the function to create a display string for a given choice.
         /// </summary>