InputRoll - don't highlight past RowCount!

BizHawk.Client.EmuHawk/tools/TAStudio/InputRoll.cs

@@ -1291,6 +1291,8 @@ namespace BizHawk.Client.EmuHawk
 		/// </summary>
 		/// <param name="cell">The cell to select.</param>
 		private void SelectCell(Cell cell, bool toggle = false)
+		{
+			if (cell.RowIndex.HasValue && cell.RowIndex < RowCount)
 			{
 				if (!MultiSelect)
 				{
@@ -1342,6 +1344,7 @@ namespace BizHawk.Client.EmuHawk
 
 				SelectedIndexChanged(this, new EventArgs());
 			}
+		}
 
 		/// <summary>
 		/// Bool that indicates if CurrentCell is a Column Cell.