public void Validate( ref TextBlock[,] textblocks, List<Point> alreadyUsedPoints )
 {
     var laidPoints = new List<Point>();
     for(var i = 0; i < textblocks.GetLength(1); i++)
     {
         for(var j = 0; j < textblocks.GetLength(0); j++)
         {
             if(!Util.IsEmpty(textblocks[j, i]?.Text))
             {
                 laidPoints.Add(new Point(j,i));
             }
         }
     }
     for(var i = 0; i < textblocks.GetLength(1); i++)
     {
         for(var j = 0; j < textblocks.GetLength(0); j++)
         {
             if(App.GameModel.PlayerToMove != App.GameModel.Me)
             {
                 textblocks[j, i].AllowDrop = false;
                 continue;
             }
             // noch keine Buchstaben gelegt in diesen Zug
             switch (alreadyUsedPoints.Count)
             {
                 case 0:
                     // erster Zug ueberhaupt
                     if(App.GameModel.IsFirstMove)
                     {
                         ValidateBetweenPoints(ref textblocks, Util.NullPoint, App.GameModel.Centre, j, i);
                     }
                     // ein spaeterer Zug
                     else
                     {
                         foreach(var p2 in laidPoints)
                         {
                             var b = ValidateBetweenPoints(ref textblocks, Util.NullPoint, p2, j, i);
                             if(b) break;
                         }
                     }
                     break;
                 case 1:
                 {
                     var p1 = alreadyUsedPoints.FirstOrDefault();
                     // erster Zug ueberhaupt
                     if(App.GameModel.IsFirstMove)
                     {
                         ValidateBetweenPoints(ref textblocks, p1, App.GameModel.Centre, j, i);
                     }
                     // ein spaeterer Zug
                     else
                     {
                         // Alle Punkt,in gleicher Spalte oder Zeile, die 7 Einheiten entfernt sind
                         var endPoints = laidPoints.Where(p => ( Util.DoubleCompare(p.X, p1.X) || Util.DoubleCompare(p.Y, p1.Y) ) && Util.CalcDistance(p, p1) <= 7 && Util.CalcDistance(p, p1) > 0);
                         foreach(var p2 in endPoints)
                         {
                             var b = ValidateBetweenPoints(ref textblocks, p1, p2, j, i);
                             if(b) break;
                         }
                     }
                 }
                     break;
                 default:
                 {
                     var p1 = alreadyUsedPoints.ElementAtOrDefault(0);
                     var p2 = alreadyUsedPoints.ElementAtOrDefault(1);
                     var d = Util.PointRelativeTo(p1, p2);
                     // horizontal
                     if (d == Util.Direction.Left || d == Util.Direction.Right)
                     {
                         var leftestPoint = Util.MinPoint(alreadyUsedPoints, Util.Axis.X);
                         var rightestPoint = Util.MaxPoint(alreadyUsedPoints, Util.Axis.X);
                         ValidateBetweenPoints(ref textblocks, leftestPoint, rightestPoint, j, i);
                     }
                     // vertikal
                     else if (d == Util.Direction.Top || d == Util.Direction.Bottom)
                     {
                         var highestPoint = Util.MinPoint(alreadyUsedPoints, Util.Axis.Y);
                         var lowestPoint = Util.MaxPoint(alreadyUsedPoints, Util.Axis.Y);
                         ValidateBetweenPoints(ref textblocks, highestPoint, lowestPoint, j, i);
                     }
                 }
                     break;
             }
         }
     }
 }