Disabled Hover (#define HOVER).

Added Color.GetHighlightColor. Simple implementation for now. Needs to be more robust.

Terminal.Gui/Drawing/Color.cs

@@ -6,6 +6,7 @@ using System.Numerics;
 using System.Runtime.CompilerServices;
 using System.Runtime.InteropServices;
 using System.Text.Json.Serialization;
+using ColorHelper;
 
 namespace Terminal.Gui;
 
@@ -237,6 +238,27 @@ public readonly partial record struct Color : ISpanParsable<Color>, IUtf8SpanPar
     [SkipLocalsInit]
     private static float CalculateColorDistance (in Vector4 color1, in Vector4 color2) { return Vector4.Distance (color1, color2); }
 
+    /// <summary>
+    /// Gets a color that is the same hue as the current color, but with a different lightness.
+    /// </summary>
+    /// <returns></returns>
+    public Color GetHighlightColor ()
+    {
+        // TODO: This is a temporary implementation; just enough to show how it could work. 
+        var hsl = ColorHelper.ColorConverter.RgbToHsl(new RGB (R, G, B));
+
+        var amount = .7;
+        if (hsl.L < 50)
+        {
+            amount += 1;
+        }
+        hsl.L = (byte)(hsl.L * amount);
+
+        var rgb = ColorHelper.ColorConverter.HslToRgb (hsl);
+        return new (rgb.R, rgb.G, rgb.B);
+
+    }
+
     #region Legacy Color Names
 
     /// <summary>The black color.</summary>

Terminal.Gui/Terminal.Gui.csproj

@@ -44,6 +44,7 @@
   <!-- Dependencies -->
   <!-- =================================================================== -->
   <ItemGroup>
+    <PackageReference Include="ColorHelper" Version="1.8.1" />
     <PackageReference Include="JetBrains.Annotations" Version="2023.3.0" />
     <!-- Enable Nuget Source Link for github -->
     <PackageReference Include="Microsoft.SourceLink.GitHub" Version="8.0.0" PrivateAssets="All" />

Terminal.Gui/View/Adornment/Border.cs

@@ -73,11 +73,13 @@ public class Border : Adornment
     /// <inheritdoc/>
     public override void BeginInit ()
     {
+#if HOVER
         // TOOD: Hack - make Arragnement overidable
         if ((Parent?.Arrangement & ViewArrangement.Movable) != 0)
         {
             HighlightStyle |= HighlightStyle.Hover;
-        }
+        }   
+#endif
 
         base.BeginInit ();
 
@@ -208,6 +210,7 @@ public class Border : Adornment
             }
             LineStyle = LineStyle.Heavy;
         }
+#if HOVER
         else if (e.HighlightStyle.HasFlag (HighlightStyle.Hover))
         {
             if (!_savedHighlightLineStyle.HasValue)
@@ -216,6 +219,7 @@ public class Border : Adornment
             }
             LineStyle = LineStyle.Double;
         }
+#endif
 
         if (e.HighlightStyle == HighlightStyle.None && _savedHighlightLineStyle.HasValue)
         {
@@ -339,7 +343,7 @@ public class Border : Adornment
         }
     }
 
-    #endregion Mouse Support
+#endregion Mouse Support
 
     /// <inheritdoc/>
     public override void OnDrawContent (Rectangle contentArea)

Terminal.Gui/View/ViewMouse.cs

@@ -13,10 +13,12 @@ public enum HighlightStyle
     /// </summary>
     None = 0,
 
+#if HOVER
     /// <summary>
     /// The mouse is hovering over the view.
     /// </summary>
     Hover = 1,
+#endif
 
     /// <summary>
     /// The mouse is pressed within the <see cref="View.Bounds"/>.
@@ -95,11 +97,15 @@ public partial class View
             return true;
         }
 
+#if HOVER
         if (HighlightStyle.HasFlag(HighlightStyle.Hover))
         {
-            SetHighlight (HighlightStyle.Hover);
+            if (SetHighlight (HighlightStyle.Hover))
+            {
+                return true;
+            }
         }
-
+#endif
         return false;
     }
 
@@ -160,15 +166,16 @@ public partial class View
             return false;
         }
 
-        if (OnMouseEnter (mouseEvent) == true)
+        if (OnMouseLeave (mouseEvent) == true)      
         {
             return true;
         }
-
+#if HOVER
         if (HighlightStyle.HasFlag (HighlightStyle.Hover))
         {
             SetHighlight (HighlightStyle.None);
         }
+#endif
 
         return false;
     }
@@ -322,11 +329,18 @@ public partial class View
 
             if (Bounds.Contains (mouseEvent.X, mouseEvent.Y))
             {
-                SetHighlight (HighlightStyle.HasFlag(HighlightStyle.Pressed) ? HighlightStyle.Pressed : HighlightStyle.None);
+                if (SetHighlight (HighlightStyle.HasFlag (HighlightStyle.Pressed) ? HighlightStyle.Pressed : HighlightStyle.None) == true)
+                {
+                    return true;
+                }
             }
             else
             {
-                SetHighlight (HighlightStyle.HasFlag (HighlightStyle.PressedOutside) ? HighlightStyle.PressedOutside : HighlightStyle.None);
+                if (SetHighlight (HighlightStyle.HasFlag (HighlightStyle.PressedOutside) ? HighlightStyle.PressedOutside : HighlightStyle.None) == true)
+
+                {
+                    return true;
+                }
             }
 
             if (WantContinuousButtonPressed && Application.MouseGrabView == this)
@@ -387,7 +401,11 @@ public partial class View
         {
             // We're grabbed. Clicked event comes after the last Release. This is our signal to ungrab
             Application.UngrabMouse ();
-            SetHighlight (HighlightStyle.None);
+
+            if (SetHighlight (HighlightStyle.None))
+            {
+                return true;
+            }
 
             // If mouse is still in bounds, click
             if (!WantContinuousButtonPressed && Bounds.Contains (mouseEvent.X, mouseEvent.Y))
@@ -418,16 +436,18 @@ public partial class View
     ///         Marked internal just to support unit tests
     ///     </para>
     /// </remarks>
-    internal void SetHighlight (HighlightStyle style)
+    /// <returns><see langword="true"/>, if the Highlight event was handled, <see langword="false"/> otherwise.</returns>
+
+    internal bool SetHighlight (HighlightStyle style)
     {
         // TODO: Make the highlight colors configurable
 
         // Enable override via virtual method and/or event
         if (OnHighlight (style) == true)
         {
-            return;
+            return true;
         }
-
+#if HOVER
         if (style.HasFlag (HighlightStyle.Hover))
         {
             if (_savedHighlightColorScheme is null && ColorScheme is { })
@@ -436,15 +456,17 @@ public partial class View
 
                 var cs = new ColorScheme (ColorScheme)
                 {
-                    Normal = new (ColorName.BrightRed, ColorName.Black),
+                    Normal = GetFocusColor (),
+                    HotNormal = ColorScheme.HotFocus
                 };
                 ColorScheme = cs;
             }
-        }
 
+            return true;
+        }
+#endif 
         if (style.HasFlag (HighlightStyle.Pressed) || style.HasFlag (HighlightStyle.PressedOutside))
         {
-
             if (_savedHighlightColorScheme is null && ColorScheme is { })
             {
                 _savedHighlightColorScheme ??= ColorScheme;
@@ -453,7 +475,7 @@ public partial class View
                 {
                     var cs = new ColorScheme (ColorScheme)
                     {
-                        Focus = new (ColorScheme.Normal.Foreground, ColorScheme.Focus.Background),
+                        Focus = new (ColorScheme.Focus.Foreground.GetHighlightColor (), ColorScheme.Focus.Background.GetHighlightColor ()),
                     };
                     ColorScheme = cs;
                 }
@@ -466,9 +488,12 @@ public partial class View
                     };
                     ColorScheme = cs;
                 }
+
+                return true;
             }
         }
 
+
         if (style == HighlightStyle.None)
         {
             // Unhighlight
@@ -478,6 +503,8 @@ public partial class View
                 _savedHighlightColorScheme = null;
             }
         }
+
+        return false;
     }
 
     /// <summary>

Terminal.Gui/Views/Button.cs

@@ -54,8 +54,9 @@ public class Button : View
         CanFocus = true;
         AutoSize = true;
         HighlightStyle |= HighlightStyle.Pressed;
+#if HOVER
         HighlightStyle |= HighlightStyle.Hover;
-
+#endif
         // Override default behavior of View
         AddCommand (Command.HotKey, () =>
                                      {

UICatalog/Scenarios/TrueColors.cs

@@ -67,6 +67,14 @@ public class TrueColors : Scenario
                  new Label { X = Pos.AnchorEnd (44), Y = 6, Text = "Blue:" }
                 );
 
+        Win.Add (
+                 new Label { X = Pos.AnchorEnd (44), Y = 8, Text = "Darker:" }
+                );
+
+        Win.Add (
+                 new Label { X = Pos.AnchorEnd (44), Y = 9, Text = "Lighter:" }
+                );
+
         var lblRed = new Label { X = Pos.AnchorEnd (32), Y = 4, Text = "na" };
         Win.Add (lblRed);
         var lblGreen = new Label { X = Pos.AnchorEnd (32), Y = 5, Text = "na" };
@@ -74,9 +82,31 @@ public class TrueColors : Scenario
         var lblBlue = new Label { X = Pos.AnchorEnd (32), Y = 6, Text = "na" };
         Win.Add (lblBlue);
 
+        var lblDarker = new Label { X = Pos.AnchorEnd (32), Y = 8, Text = "     " };
+        Win.Add (lblDarker);
+
+        var lblLighter = new Label { X = Pos.AnchorEnd (32), Y = 9, Text = "    " };
+        Win.Add (lblLighter);
+
         Application.MouseEvent += (s, e) =>
                                   {
-                                      if (e.View != null)
+                                      if (e.View == null)
+                                      {
+                                          return;
+                                      }
+                                      if (e.Flags == MouseFlags.Button1Clicked)
+                                      {
+                                          Attribute normal = e.View.GetNormalColor ();
+                                          
+                                          lblLighter.ColorScheme = new ColorScheme(e.View.ColorScheme)
+                                          {
+                                              Normal = new Attribute (
+                                                                      normal.Foreground,
+                                                                      normal.Background.GetHighlightColor ()
+                                                                     )
+                                          };
+                                      }
+                                      else
                                       {
                                           Attribute normal = e.View.GetNormalColor ();
                                           lblRed.Text = normal.Foreground.R.ToString ();