//This is in the form class:
public static void notifyChange()
        {
        //Error here: "An object reference is required for the non-static field, method, or property
        //'Level_Editor.MapEditor.ChangeIndicator'
            ChangeIndicator.Text = status;
        }

//Here's the code in the XNA game that needs to use notifyChange to change the text in the form:
//if the mouse coordinates for the world are actually in the world...
                if (Camera.WorldRectangle.Contains((int)mouseLoc.X, (int)mouseLoc.Y))
                {
                    //if the left button is pressed...
                    if (ms.LeftButton == ButtonState.Pressed)
                    {
                        isChanged = true;
                        MapEditor.notifyChange();
                        //Place tile at cell pointed at by the mouse
                        TileMap.SetTileAtCell(
                            TileMap.GetCellByPixelX((int)mouseLoc.X),
                            TileMap.GetCellByPixelY((int)mouseLoc.Y),
                        DrawLayer, DrawTile);
                    }

                    //if we pressed the right-mouse button & we have not been holding it down...
                    if ((ms.RightButton == ButtonState.Pressed) &&
                        (lastMouseState.RightButton != ButtonState.Released))
                    {
                        isChanged = true;
                        MapEditor.notifyChange();
                        //if we are also in Code Editing mode...
                        if (EditingCode)
                        {
                            //Set the code value of the selected tile to the current code value
                            // within the editor window
                            TileMap.GetMapSquareAtCell(
                                TileMap.GetCellByPixelX((int)mouseLoc.X),
                                TileMap.GetCellByPixelY((int)mouseLoc.Y)
                                ).CodeValue = CurrentCodeValue;
                        }
                        else
                        {
                            //Check the tile chosen upon click then paint the opposite of it
                            if (!painting)
                            {
                                paintType = !(TileMap.GetMapSquareAtCell(
                                TileMap.GetCellByPixelX((int)mouseLoc.X),
                                TileMap.GetCellByPixelY((int)mouseLoc.Y)
                                ).Passable);
                                painting = true;
                            }
                            if (painting)
                            {
                                TileMap.GetMapSquareAtCell(
                                TileMap.GetCellByPixelX((int)mouseLoc.X),
                                TileMap.GetCellByPixelY((int)mouseLoc.Y)
                                ).Passable = paintType;
                            }
                        }
                    }

                    if (ms.RightButton == ButtonState.Released)
                    {
                        painting = false;
                    }