Fixed wrong panel2 MinSize calculation when there is a border

Terminal.Gui/Views/SplitContainer.cs

@@ -228,6 +228,12 @@ namespace Terminal.Gui {
 				return (Pos)Math.Min (splitterPanels [0].MinSize.Anchor (availableSpace), availableSpace);
 			}
 
+			// if there is a border then 2 screen units are taken occupied
+			// by the border around the edge (one on left, one on right).
+			if (HasBorder ()) {
+				availableSpace -= 2;
+			}
+
 			// bad position because not enough space for splitterPanels[1]
 			if (availableSpace - idealPosition <= splitterPanels [1].MinSize.Anchor (availableSpace)) {
 
@@ -324,20 +330,15 @@ namespace Terminal.Gui {
 				LayoutStarted += (e) => {
 					moveRuneRenderLocation = null;
 					if (Orientation == Orientation.Horizontal) {
-						StartingAnchor = ParentHasBorder () ? Driver.LeftTee : (Rune?)null;
-						EndingAnchor = ParentHasBorder () ? Driver.RightTee : (Rune?)null;
+						StartingAnchor = parent.HasBorder () ? Driver.LeftTee : (Rune?)null;
+						EndingAnchor = parent.HasBorder () ? Driver.RightTee : (Rune?)null;
 					} else {
-						StartingAnchor = ParentHasBorder () ? Driver.TopTee : (Rune?)null;
-						EndingAnchor = ParentHasBorder () ? Driver.BottomTee : (Rune?)null;
+						StartingAnchor = parent.HasBorder () ? Driver.TopTee : (Rune?)null;
+						EndingAnchor = parent.HasBorder () ? Driver.BottomTee : (Rune?)null;
 					}
 				};
 			}
 
-			private bool ParentHasBorder ()
-			{
-				return parent.Border != null && parent.Border.BorderStyle != BorderStyle.None;
-			}
-
 			public override bool ProcessKey (KeyEvent kb)
 			{
 				if (!CanFocus || !HasFocus) {
@@ -518,6 +519,10 @@ namespace Terminal.Gui {
 			}
 		}
 
+		private bool HasBorder ()
+		{
+			return Border != null && Border.BorderStyle != BorderStyle.None;
+		}
 	}
 
 	/// <summary>

UnitTests/SplitContainerTests.cs

@@ -246,6 +246,139 @@ namespace UnitTests {
        │     ";
 
 			TestHelpers.AssertDriverContentsAre (looksLike, output);
+		}
+
+
+		[Fact, AutoInitShutdown]
+		public void TestSplitContainer_Vertical_Panel1MinSize_Absolute_WithBorder ()
+		{
+			var splitContainer = Get11By3SplitContainer (out var line,true);
+			SetInputFocusLine (splitContainer);
+			splitContainer.Panels [0].MinSize = 5;
+
+			// distance is too small (below 5)
+			splitContainer.SplitterDistance = 2;
+
+			// Should bound the value to the minimum distance
+			Assert.Equal (5, splitContainer.SplitterDistance);
+
+			splitContainer.Redraw (splitContainer.Bounds);
+
+			// so should ignore the 2 distance and stick to 5
+			string looksLike =
+@"
+┌─────┬───┐
+│11111◊222│
+└─────┴───┘";
+			TestHelpers.AssertDriverContentsAre (looksLike, output);
+
+			// Keyboard movement on splitter should have no effect because it
+			// would take us below the minimum splitter size
+			line.ProcessKey (new KeyEvent (Key.CursorLeft, new KeyModifiers ()));
+			splitContainer.SetNeedsDisplay ();
+			splitContainer.Redraw (splitContainer.Bounds);
+			TestHelpers.AssertDriverContentsAre (looksLike, output);
+
+			// but we can continue to move the splitter right if we want
+			line.ProcessKey (new KeyEvent (Key.CursorRight, new KeyModifiers ()));
+			splitContainer.SetNeedsDisplay ();
+			splitContainer.Redraw (splitContainer.Bounds);
+
+			looksLike =
+@"
+┌──────┬──┐
+│111111◊22│
+└──────┴──┘";
+
+			TestHelpers.AssertDriverContentsAre (looksLike, output);
+		}
+
+		[Fact, AutoInitShutdown]
+		public void TestSplitContainer_Vertical_Panel2MinSize_Absolute ()
+		{
+			var splitContainer = Get11By3SplitContainer (out var line);
+			SetInputFocusLine (splitContainer);
+			splitContainer.Panels [1].MinSize = 6;
+
+			// distance leaves too little space for panel2 (less than 6 would remain)
+			splitContainer.SplitterDistance = 8;
+
+			// Should bound the value to the minimum distance
+			Assert.Equal (4, splitContainer.SplitterDistance);
+
+			splitContainer.Redraw (splitContainer.Bounds);
+
+			// so should ignore the 2 distance and stick to 6
+			string looksLike =
+@"
+1111│222222
+    ◊
+    │     ";
+			TestHelpers.AssertDriverContentsAre (looksLike, output);
+
+			// Keyboard movement on splitter should have no effect because it
+			// would take us below the minimum splitter size
+			line.ProcessKey (new KeyEvent (Key.CursorRight, new KeyModifiers ()));
+			splitContainer.SetNeedsDisplay ();
+			splitContainer.Redraw (splitContainer.Bounds);
+			TestHelpers.AssertDriverContentsAre (looksLike, output);
+
+			// but we can continue to move the splitter left if we want
+			line.ProcessKey (new KeyEvent (Key.CursorLeft, new KeyModifiers ()));
+			splitContainer.SetNeedsDisplay ();
+			splitContainer.Redraw (splitContainer.Bounds);
+
+			looksLike =
+@"
+111│2222222
+   ◊
+   │     ";
+
+			TestHelpers.AssertDriverContentsAre (looksLike, output);
+
+		}
+		[Fact, AutoInitShutdown]
+		public void TestSplitContainer_Vertical_Panel2MinSize_Absolute_WithBorder ()
+		{
+			var splitContainer = Get11By3SplitContainer (out var line, true);
+			SetInputFocusLine (splitContainer);
+			splitContainer.Panels [1].MinSize = 5;
+
+			// distance leaves too little space for panel2 (less than 5 would remain)
+			splitContainer.SplitterDistance = 8;
+
+			// Should bound the value to the minimum distance
+			Assert.Equal (3, splitContainer.SplitterDistance);
+
+			splitContainer.Redraw (splitContainer.Bounds);
+
+			// so should ignore the 2 distance and stick to 6
+			string looksLike =
+@"
+┌───┬─────┐
+│111◊22222│
+└───┴─────┘";
+			TestHelpers.AssertDriverContentsAre (looksLike, output);
+
+			// Keyboard movement on splitter should have no effect because it
+			// would take us below the minimum splitter size
+			line.ProcessKey (new KeyEvent (Key.CursorRight, new KeyModifiers ()));
+			splitContainer.SetNeedsDisplay ();
+			splitContainer.Redraw (splitContainer.Bounds);
+			TestHelpers.AssertDriverContentsAre (looksLike, output);
+
+			// but we can continue to move the splitter left if we want
+			line.ProcessKey (new KeyEvent (Key.CursorLeft, new KeyModifiers ()));
+			splitContainer.SetNeedsDisplay ();
+			splitContainer.Redraw (splitContainer.Bounds);
+
+			looksLike =
+@"
+┌──┬──────┐
+│11◊222222│
+└──┴──────┘";
+
+			TestHelpers.AssertDriverContentsAre (looksLike, output);
 
 		}
 		[Fact, AutoInitShutdown]