fix(controls): table border transparency and scroll event bubbling

TableControl.Rendering: use effectiveBg (transparent) instead of bgColor
for border lines, allowing gradient backgrounds to show through.

TableControl.Mouse: return false when scroll offset didn't change,
allowing parent ScrollablePanel to handle the event.

MultilineEditControl.Mouse: same fix — bubble scroll events at limits
instead of unconditionally consuming them.

Author: nickprotop

SharpConsoleUI/Controls/MultilineEdit/MultilineEditControl.Mouse.cs

@@ -398,8 +398,9 @@ public bool ProcessMouseEvent(MouseEventArgs args)
 					_skipUpdateScrollPositionsInRender = true;
 					_verticalScrollOffset -= scrollAmount;
 					Container?.Invalidate(true);
+					return true;
 				}
-				return true;
+				return false; // at top, bubble to parent
 			}
 
 			// Mouse wheel down
@@ -414,8 +415,9 @@ public bool ProcessMouseEvent(MouseEventArgs args)
 					_skipUpdateScrollPositionsInRender = true;
 					_verticalScrollOffset += scrollAmount;
 					Container?.Invalidate(true);
+					return true;
 				}
-				return true;
+				return false; // at bottom, bubble to parent
 			}
 
 			// Regular mouse move (no drag)

SharpConsoleUI/Controls/TableControl/TableControl.Mouse.cs

@@ -120,27 +120,39 @@ public bool ProcessMouseEvent(MouseEventArgs args)
 		{
 			if (args.HasFlag(MouseFlags.ButtonShift))
 			{
+				int oldH = _horizontalScrollOffset;
 				_horizontalScrollOffset = Math.Max(0, _horizontalScrollOffset - 3);
-				Container?.Invalidate(true);
-				return true;
+				if (_horizontalScrollOffset != oldH)
+				{
+					Container?.Invalidate(true);
+					return true;
+				}
+				return false; // bubble to parent
 			}
 
+			int oldOffset = _scrollOffset;
 			ScrollOffset = Math.Max(0, _scrollOffset - 3);
-			return true;
+			return _scrollOffset != oldOffset; // bubble if didn't scroll
 		}
 
 		if (args.HasFlag(MouseFlags.WheeledDown))
 		{
 			if (args.HasFlag(MouseFlags.ButtonShift))
 			{
+				int oldH = _horizontalScrollOffset;
 				_horizontalScrollOffset += 3;
-				Container?.Invalidate(true);
-				return true;
+				if (_horizontalScrollOffset != oldH)
+				{
+					Container?.Invalidate(true);
+					return true;
+				}
+				return false; // bubble to parent
 			}
 
+			int oldOffset = _scrollOffset;
 			int maxOffset = Math.Max(0, RowCount - GetVisibleRowCount());
 			ScrollOffset = Math.Min(maxOffset, _scrollOffset + 3);
-			return true;
+			return _scrollOffset != oldOffset; // bubble if didn't scroll
 		}
 
 		// Left-click

SharpConsoleUI/Controls/TableControl/TableControl.Rendering.cs

@@ -587,7 +587,7 @@ void FillSideMargins(int y)
 		if (hasBorder && currentY < maxY)
 		{
 			FillSideMargins(currentY);
-			DrawHorizontalLine(buffer, startX, currentY, colWidths, clipRect, box, borderColor, bgColor,
+			DrawHorizontalLine(buffer, startX, currentY, colWidths, clipRect, box, borderColor, effectiveBg,
 				box.TopLeft, box.TopTee, box.TopRight, box.Horizontal);
 			currentY++;
 		}
@@ -626,7 +626,7 @@ void FillSideMargins(int y)
 				}
 			}
 
-			DrawDataRow(buffer, startX, currentY, colWidths, clipRect, box, borderColor, bgColor,
+			DrawDataRow(buffer, startX, currentY, colWidths, clipRect, box, borderColor, effectiveBg,
 				headerCells, colSnapshot, headerFg, headerBg, hasBorder);
 
 			// Update column rendered positions for hit testing (always, including DataSource mode)
@@ -653,7 +653,7 @@ void FillSideMargins(int y)
 			if (hasBorder && currentY < maxY)
 			{
 				FillSideMargins(currentY);
-				DrawHorizontalLine(buffer, startX, currentY, colWidths, clipRect, box, borderColor, bgColor,
+				DrawHorizontalLine(buffer, startX, currentY, colWidths, clipRect, box, borderColor, effectiveBg,
 					box.LeftTee, box.Cross, box.RightTee, box.Horizontal);
 				currentY++;
 			}
@@ -675,7 +675,7 @@ void FillSideMargins(int y)
 			if (displayR > startRow && _showRowSeparators && hasBorder && currentY < maxY)
 			{
 				FillSideMargins(currentY);
-				DrawHorizontalLine(buffer, startX, currentY, colWidths, clipRect, box, borderColor, bgColor,
+				DrawHorizontalLine(buffer, startX, currentY, colWidths, clipRect, box, borderColor, effectiveBg,
 					box.LeftTee, box.Cross, box.RightTee, box.Horizontal);
 				currentY++;
 			}
@@ -795,7 +795,7 @@ void FillSideMargins(int y)
 			{
 				FillSideMargins(currentY);
 				DrawMergedHorizontalLine(buffer, startX, currentY, colWidths, clipRect,
-					box, borderColor, bgColor, box.LeftTee, box.RightTee, box.Horizontal);
+					box, borderColor, effectiveBg, box.LeftTee, box.RightTee, box.Horizontal);
 				currentY++;
 			}
 
@@ -817,15 +817,15 @@ void FillSideMargins(int y)
 			{
 				FillSideMargins(currentY);
 				DrawMergedHorizontalLine(buffer, startX, currentY, colWidths, clipRect,
-					box, borderColor, bgColor, box.BottomLeft, box.BottomRight, box.Horizontal);
+					box, borderColor, effectiveBg, box.BottomLeft, box.BottomRight, box.Horizontal);
 				currentY++;
 			}
 		}
 		else if (hasBorder && currentY < maxY)
 		{
 			// Standard bottom border with column tees
 			FillSideMargins(currentY);
-			DrawHorizontalLine(buffer, startX, currentY, colWidths, clipRect, box, borderColor, bgColor,
+			DrawHorizontalLine(buffer, startX, currentY, colWidths, clipRect, box, borderColor, effectiveBg,
 				box.BottomLeft, box.BottomTee, box.BottomRight, box.Horizontal);
 			currentY++;
 		}
@@ -861,7 +861,7 @@ void FillSideMargins(int y)
 			{
 				int cornerX = startX + contentWidth;
 				if (cornerX >= clipRect.X && cornerX < clipRect.Right)
-					buffer.SetNarrowCell(cornerX, currentY, ' ', fgColor, bgColor);
+					buffer.SetNarrowCell(cornerX, currentY, ' ', fgColor, effectiveBg);
 			}
 			currentY++;
 		}