My custom editor window script crashes the Editor.

Hi guys! So I have this script I want to use as a way to draw sprites in the editor to later turn these sprites into gameobjects. But now I'm trying to get the drag-and-dropping of sprites to work. That is, untill this morning when my script started to crash the Editor. I have tried to open the window in a new project, but it gave me the same results.

Code:

 public class SpritePaintingTools : EditorWindow
 {
     #region Window
     [MenuItem("Painting Tools/Sprite Painter", false, 2)]
     public static void Init()
     {
         SpritePaintingTools window = (SpritePaintingTools)GetWindow(typeof(SpritePaintingTools));
         window.Show();
         window.minSize = new Vector2(200, 250);
     }
     #endregion
 
     
     //An int to referance the button that is curantly pressed.
     int toolInt;
     //The text to fill the toolbar.
     string[] toolNames = new string[] { "Paint", "Erase", "Edit Layout" };
     //An rect to set the toolbar to.
     static Rect toolbar;
     //An rect to set the grid to.
     static Rect gridBackground;
     //Mouse offset
     public static Vector2 mouseOffset = new Vector2(1000, 1000);
     //Mouse zoom
     static float zoom;
     //The sprites in the curent editor.
     public static List<SpriteData> sprites = new List<SpriteData>();
 
 
     private void OnGUI()
     {
         #region Setting some settings
 
         #region Setting the Rects
 
         toolbar = new Rect(25, 25, position.width - 50, (position.width - 50) / 10);
         gridBackground = new Rect(25, 50 + toolbar.height, position.width - 50, position.height - toolbar.height - 75);
 
         #endregion
         #region Setting the mouse offset
 
         if (Event.current != null && Event.current.type == EventType.MouseDrag && Event.current.button == 1)
         {
             mouseOffset += Event.current.delta;
             Repaint();
         }
 
         #endregion
         #region Setting the mouse zoom
 
         float _zoom = zoom;
 
         if (Event.current.isScrollWheel)
         {
             _zoom += Event.current.delta.y;
         }
 
         #endregion
 
         #endregion
 
 
         toolInt = GUI.Toolbar(toolbar, toolInt, toolNames);
 
         GLGrid.Generate(gridBackground, 1000, 10, 5, mouseOffset);
         var objs = SpriteHandeling.DropZone(gridBackground);
         if (objs != null)
         {
             foreach (var o in objs)
             {
                 int i = 0;
                 if (o is Texture2D)
                 {
                     sprites.Add(new SpriteData(new Rect(50 * i, 0, 50, 50), o as Texture2D));
                     i++;
                 }
             }
         }
 
         SpriteHandeling.DrawSprites(sprites.ToArray());
 
         if (GUI.changed)
             Repaint();
     }
 
     class GLGrid
     {
         static Color _background = new Color(.4f, .4f, .4f);
         static Color _smallLine = new Color(.35f, .35f, .35f);
         static Color _largeline = new Color(.3f, .3f, .3f);
 
         public static void Generate(Rect rect, float windowSize, float smallTileSize, int subdivisions, Vector2 offset)
         {
             //Draw the background
             EditorGUI.DrawRect(rect, _background);
             
             // Calculate large tile size
             float largeTileSize = smallTileSize * (float)subdivisions;
 
             //Make the glitchy side effects not happen by not letting it go into the -.
             if (offset.x < 0)
             {
                 mouseOffset = new Vector2(0, offset.y);
             }
             if (offset.y < 0)
             {
                 mouseOffset = new Vector2(offset.x, 0);
             }
             if (offset.x > windowSize)
             {
                 mouseOffset = new Vector2(1000, offset.y);
             }
             if (offset.y > windowSize)
             {
                 mouseOffset = new Vector2(offset.x, 1000);
             }
             
 
             GL.PushMatrix();
             GL.LoadPixelMatrix();
 
             // Vertical small lines
             for (float x = 0 + offset.x % smallTileSize + 1; x < rect.width; x += smallTileSize * zoom)
             {
                 GL.Begin(GL.LINES);
                 GL.Color(_smallLine);
                 GL.Vertex3(rect.x + x, rect.y + 1, 0);
                 GL.Vertex3(rect.x + x, rect.y + rect.height, 0);
                 GL.End();
             }
             // Horizontal small lines
             for (float y = 0 + offset.y % smallTileSize + 1; y < rect.height; y += smallTileSize * zoom)
             {
                 GL.Begin(GL.LINES);
                 GL.Color(_smallLine);
                 GL.Vertex3(rect.x, rect.y + y, 0);
                 GL.Vertex3(rect.x + rect.width, rect.y + y, 0);
                 GL.End();
             }
 
             // Vertical large lines
             for (float x = 0 + offset.x % largeTileSize + 1; x < rect.width; x += largeTileSize * zoom)
             {
                 GL.Begin(GL.LINES);
                 GL.Color(_largeline);
                 GL.Vertex3(rect.x + x, rect.y + 1, 0);
                 GL.Vertex3(rect.x + x, rect.y + rect.height, 0);
                 GL.End();
             }
             // Horizontal large lines
             for (float y = 0 + offset.y % largeTileSize + 1; y < rect.height; y += largeTileSize * zoom)
             {
                 GL.Begin(GL.LINES);
                 GL.Color(_largeline);
                 GL.Vertex3(rect.x, rect.y + y, 0);
                 GL.Vertex3(rect.x + rect.width, rect.y + y, 0);
                 GL.End();
             }
 
             GL.PopMatrix();
         }
     }
     class SpriteHandeling
     {
         public static object[] DropZone(Rect rect)
         {
             Rect drop_area = rect;
 
             var eventType = Event.current.type;
             bool isAccepted = false;
             if (drop_area.Contains(Event.current.mousePosition))
             {
                 if (eventType == EventType.DragUpdated || eventType == EventType.DragPerform)
                 {
                     DragAndDrop.visualMode = DragAndDropVisualMode.Copy;
                     if (eventType == EventType.DragPerform)
                     {
                         DragAndDrop.AcceptDrag();
                         isAccepted = true;
                     }
 
                     Event.current.Use();
                 }
             }
             return isAccepted ? DragAndDrop.objectReferences : null;
         }
         public static void DrawSprites(SpriteData[] sprites)
         {
             if (sprites != null)
             {
                 foreach (SpriteData DT in sprites)
                 {
                     Rect _location = DT.location;
                     _location.x += gridBackground.x + mouseOffset.x - 1000;
                     _location.y += gridBackground.y + mouseOffset.y - 1000;
                     
                     GUI.DrawTexture(_location, DT.picture);
                 }
 
                 focusedWindow.Repaint();
             }
         }
     }
 
     public class SpriteData
     {
         public Rect location;
         public Texture2D picture;
 
         public SpriteData(Rect location, Texture2D pic)
         {
             this.location = location;
             this.picture = pic;
         }
     }
 }

If you guys know what I'm doing wrong I would very much like to know. I have been working on this for AGES...