Adds ViewportSettings.Transparent (#3886)

UnitTests/View/Draw/DrawEventTests.cs

@@ -0,0 +1,32 @@
+#nullable enable
+using System.Text;
+using Xunit.Abstractions;
+
+namespace Terminal.Gui.ViewTests;
+
+[Trait ("Category", "Output")]
+public class DrawEventTests (ITestOutputHelper _output)
+{
+
+    [Fact]
+    [AutoInitShutdown]
+    public void DrawContentComplete_Event_Is_Always_Called ()
+    {
+        var viewCalled = false;
+        var tvCalled = false;
+
+        var view = new View { Width = 10, Height = 10, Text = "View" };
+        view.DrawComplete += (s, e) => viewCalled = true;
+        var tv = new TextView { Y = 11, Width = 10, Height = 10 };
+        tv.DrawComplete += (s, e) => tvCalled = true;
+
+        var top = new Toplevel ();
+        top.Add (view, tv);
+        RunState runState = Application.Begin (top);
+        Application.RunIteration (ref runState);
+
+        Assert.True (viewCalled);
+        Assert.True (tvCalled);
+        top.Dispose ();
+    }
+}