Highlight stuff to distinct files

Terminal.Gui/View/HighlightEventArgs.cs

@@ -0,0 +1,10 @@
+namespace Terminal.Gui;
+
+/// <summary>
+/// Event arguments for the <see cref="View.Highlight"/> event.
+/// </summary>
+public class HighlightEventArgs : CancelEventArgs<HighlightStyle>
+{
+    /// <inheritdoc />
+    public HighlightEventArgs (HighlightStyle currentValue, HighlightStyle newValue) : base (currentValue, newValue) { }
+}

Terminal.Gui/View/HighlightStyle.cs

@@ -0,0 +1,30 @@
+namespace Terminal.Gui;
+
+/// <summary>
+/// Describes the highlight style of a view.
+/// </summary>
+[Flags]
+public enum HighlightStyle
+{
+    /// <summary>
+    /// No highlight.
+    /// </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.Viewport"/>.
+    /// </summary>
+    Pressed = 2,
+
+    /// <summary>
+    /// The mouse is pressed but moved outside the <see cref="View.Viewport"/>.
+    /// </summary>
+    PressedOutside = 4
+}