Keep Force16Colors set across apps to ease debugging of flicker issue

Terminal.Gui/Application.cs

@@ -133,7 +133,7 @@ public static partial class Application
 
         // Don't reset ForceDriver; it needs to be set before Init is called.
         //ForceDriver = string.Empty;
-        Force16Colors = false;
+        //Force16Colors = false;
         _forceFakeConsole = false;
 
         // Run State stuff

Terminal.Gui/Drawing/Thickness.cs

@@ -161,6 +161,7 @@ public class Thickness : IEquatable<Thickness>
             Application.Driver.FillRect (rect with { Height = Math.Min (rect.Height, Top) }, topChar);
         }
 
+        // Draw the Left side
         // Draw the Left side
         if (Left > 0)
         {

UnitTests/Application/ApplicationTests.cs

@@ -172,7 +172,8 @@ public class ApplicationTests
 
             // Don't check Application.ForceDriver
             // Assert.Empty (Application.ForceDriver);
-            Assert.False (Application.Force16Colors);
+            // Don't check Application.Force16Colors
+            //Assert.False (Application.Force16Colors);
             Assert.Null (Application.Driver);
             Assert.Null (Application.MainLoop);
             Assert.False (Application.EndAfterFirstIteration);