Don't hardcode colours in InputRoll

src/BizHawk.Client.EmuHawk/CustomControls/InputRoll/InputRoll.Drawing.cs

@@ -14,8 +14,8 @@ namespace BizHawk.Client.EmuHawk
 			using (_renderer.LockGraphics(e.Graphics))
 			{
 				// White Background
-				_renderer.SetBrush(Color.White);
-				_renderer.SetSolidPen(Color.White);
+				_renderer.SetBrush(_backColor);
+				_renderer.SetSolidPen(_backColor);
 				_renderer.FillRectangle(e.ClipRectangle);
 
 				// Lag frame calculations
@@ -510,7 +510,6 @@ namespace BizHawk.Client.EmuHawk
 
 		private void DoSelectionBG(List<RollColumn> visibleColumns, Rectangle rect)
 		{
-			Color rowColor = Color.White;
 			var visibleRows = FirstVisibleRow.RangeTo(LastVisibleRow);
 			int lastRow = -1;
 			foreach (Cell cell in _selectedItems)
@@ -527,6 +526,7 @@ namespace BizHawk.Client.EmuHawk
 				};
 				relativeCell.RowIndex -= CountLagFramesAbsolute(relativeCell.RowIndex.Value);
 
+				var rowColor = _backColor;
 				if (QueryRowBkColor != null && lastRow != cell.RowIndex.Value)
 				{
 					QueryRowBkColor(cell.RowIndex.Value, ref rowColor);
@@ -603,27 +603,21 @@ namespace BizHawk.Client.EmuHawk
 			for (int i = 0, f = 0; f < range; i++, f++)
 			{
 				f += _lagFrames[i];
-				Color rowColor = Color.White;
+				var rowColor = _backColor;
 				QueryRowBkColor?.Invoke(f + startIndex, ref rowColor);
 
 				foreach (var column in visibleColumns)
 				{
-					Color itemColor = Color.White;
+					var itemColor = rowColor;
 					QueryItemBkColor?.Invoke(f + startIndex, column, ref itemColor);
-
-					if (itemColor == Color.White)
-					{
-						itemColor = rowColor;
-					}
-					else if (itemColor.A != 255 && itemColor.A != 0)
+					if (itemColor.A is not 0 or 255)
 					{
 						float alpha = (float)itemColor.A / 255;
 						itemColor = Color.FromArgb(rowColor.R - (int)((rowColor.R - itemColor.R) * alpha),
 							rowColor.G - (int)((rowColor.G - itemColor.G) * alpha),
 							rowColor.B - (int)((rowColor.B - itemColor.B) * alpha));
 					}
-
-					if (itemColor != Color.White) // An easy optimization, don't draw unless the user specified something other than the default
+					if (itemColor != _backColor) // An easy optimization, don't draw unless the user specified something other than the default
 					{
 						var cell = new Cell
 						{

src/BizHawk.Client.EmuHawk/CustomControls/InputRoll/InputRoll.cs

@@ -31,8 +31,21 @@ namespace BizHawk.Client.EmuHawk
 		private readonly Timer _hoverTimer = new Timer();
 		private readonly byte[] _lagFrames = new byte[256]; // Large enough value that it shouldn't ever need resizing. // apparently not large enough for 4K
 
-		private readonly Color _foreColor;
-		private readonly Color _backColor;
+		private Color _backColor;
+
+		public override Color BackColor
+		{
+			get => _backColor;
+			set => base.BackColor = _backColor = value;
+		}
+
+		private Color _foreColor;
+
+		public override Color ForeColor
+		{
+			get => _foreColor;
+			set => base.ForeColor = _foreColor = value;
+		}
 
 		private RollColumns _columns = new RollColumns();
 		private bool _horizontalOrientation;
@@ -117,8 +130,18 @@ namespace BizHawk.Client.EmuHawk
 			_hoverTimer.Tick += HoverTimerEventProcessor;
 			_hoverTimer.Stop();
 
-			_foreColor = ForeColor;
-			_backColor = BackColor;
+			if (OSTailoredCode.IsUnixHost)
+			{
+				// sorry dark theme users, but this needs to be readable
+				_backColor = Color.White;
+				_foreColor = Color.Black;
+			}
+			else
+			{
+				// this is the ctor, so these reads will always return the default values
+				_backColor = base.BackColor;
+				_foreColor = base.ForeColor;
+			}
 		}
 
 		private void HoverTimerEventProcessor(object sender, EventArgs e)