Another Screensaver with WPF

using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;

namespace RZWScreenSaver{
    static class IListExtension{
        static public T[] CastToArray<T>(this IList list){
            var result = new T[list.Count];
            for(int i=0; i < result.Length; ++i)
                result[i] = (T) list[i];
            return result;
        }
        static public int IndexOf<T>(this IList list, Func<T,bool> predicate){
            for(var i=0; i < list.Count; ++i){
                if (predicate((T)list[i]))
                    return i;
            }
            return -1;
        }
        static public void Shuffle<T>(this T[] source, int pos1, int pos2, ref T[] target){
            Debug.Assert(source.Length == target.Length);
            var firstCut = Math.Min(pos1, pos2);
            var secondCut = Math.Max(pos1, pos2);
            var firstChunkLength = firstCut;
            var secondChunkLength = secondCut - firstCut;
            var thirdChunkLength = source.Length - secondCut;
            const int targetFirstChunk = 0;
            if (pos1 < pos2){
                // perform shuffle pattern 1: swap chunk #1 and #2.
                var targetSecondChunk = secondChunkLength;
                var targetThirdChunk = secondChunkLength + firstChunkLength;
                Array.Copy(source, 0, target, targetSecondChunk, firstChunkLength);
                Array.Copy(source, firstCut, target, targetFirstChunk, secondChunkLength);
                Array.Copy(source, secondCut, target, targetThirdChunk, thirdChunkLength);
            }else{
                // swap chunk #1 and #3
                var targetSecondChunk = thirdChunkLength;
                var targetThirdChunk = thirdChunkLength + secondChunkLength;
                Array.Copy(source, 0, target, targetThirdChunk, firstChunkLength);
                Array.Copy(source, firstCut, target, targetSecondChunk, secondChunkLength);
                Array.Copy(source, secondCut, target, targetFirstChunk, thirdChunkLength);
            }
        }
        static public void Swap<T>(this IList<T> list, int pos1, int pos2){
            T temp = list[pos1];
            list[pos1] = list[pos2];
            list[pos2] = temp;
        }
    }
}