private bool MouseMoveAction(int x, int y, MouseButtons b)
        {
            switch (action)
            {
            case MouseAction.Select:
                if (selrect != Rectangle.Empty)
                {
                    parent.cview.InvalidatePage(selrect);
                }

                selrect.X      = Math.Min(x, selx);
                selrect.Y      = Math.Min(y, sely);
                selrect.Width  = Math.Abs(x - selx);
                selrect.Height = Math.Abs(y - sely);
                parent.cview.InvalidatePage(selrect);
                break;

            case MouseAction.Move:

                // on first move
                if (first_move)
                {
                    if (original_selected != null)
                    {
                        parent.SelectedObjects.Remove(original_selected);
                        original_selected = null;
                    }
                    if (moveitem != null)
                    {
                        if (moveitem is IStateObject)
                        {
                            movestates[moveitem] = (moveitem as IStateObject).GetState();
                        }
                        if (!(moveitem as GuiObject).selected)
                        {
                            parent.SelectedObjects.Clear();
                            parent.SelectedObjects.Add(moveitem as GuiObject);
                        }
                    }
                    else
                    {
                        parent.SelectedObjects.Clear();
                        foreach (GuiObject t in movelist)
                        {
                            parent.SelectedObjects.Add(t);
                        }
                        foreach (GuiObject t in movelist)
                        {
                            if (t is IStateObject)
                            {
                                movestates[t] = (t as IStateObject).GetState();
                            }
                        }
                    }
                    AddAssociatedObjects();
                    first_move = false;
                }

                // usual move
                if (moveitem != null)
                {
                    moveitem.Moving(x, y, ref moveux, ref moveuy);
                }
                else
                {
                    foreach (IMoveMultiple i in movelist)
                    {
                        i.ShiftShape(x - selx, y - sely);
                    }
                    selx = x;
                    sely = y;
                }
                break;

            case MouseAction.Scroll:
                parent.cview.AdjustPageCoords(selx - x, sely - y);
                first_move = false;
                break;

            case MouseAction.CreateConnection:
                conn.Invalidate();
                conn.InvalidateTemporary();

                conn.second.item = parent.FindItem(x, y, out moveux, out moveuy, true) as IAcceptConnection;
                if (conn.second.item == null || conn.second.item == conn.first.item)
                {
                    conn.second.x    = x;
                    conn.second.y    = y;
                    conn.second.item = null;
                }
                else
                {
                    conn.second.item.coord_nearest(x, y, out conn.second.ux, out conn.second.uy);
                    conn.second.UpdatePosition(true);
                }
                conn.DoCreationFixup();
                conn.InvalidateTemporary();
                conn.Invalidate();
                break;
            }
            return(action != MouseAction.Scroll);
        }
        public override void MouseDown(int x, int y, MouseButtons b, Keys modif, int realx, int realy)
        {
            // Left mouse button

            if (action != MouseAction.None)
            {
                return;
            }

            if (b == MouseButtons.Left)
            {
                if (current_operation == MouseOperation.DrawComment || current_operation == MouseOperation.DrawPackage)
                {
                    switch (current_operation)
                    {
                    case MouseOperation.DrawComment:
                        moveitem = GuiElementFactory.CreateMemo(parent, x, y);
                        break;

                    case MouseOperation.DrawPackage:
                        moveitem = GuiElementFactory.CreatePackage(parent, x, y);
                        break;
                    }

                    first_move = true;
                    moveux     = 0;
                    moveuy     = 0;
                    action     = MouseAction.Move;
                }
                else if ((modif & Keys.Control) == Keys.Control || current_operation == MouseOperation.DrawConnection)
                {
                    conn_item = parent.FindItem(x, y, out moveux, out moveuy, true) as IAcceptConnection;
                    if (conn_item == null)
                    {
                        action = MouseAction.Scroll;
                        selx   = x;
                        sely   = y;
                        return;
                    }

                    int   ux;
                    float uy;
                    conn_item.coord_nearest(x, y, out ux, out uy);
                    action = MouseAction.CreateConnection;

                    conn = new GuiConnection(new GuiConnectionPoint(conn_item, ux, uy, 0), new GuiConnectionPoint(x, y, 1), conn_type, parent, conn_type == UmlRelationType.Attachment ? GuiConnectionStyle.Line : conn_style);
                    conn.first.item.coord_nearest(x, y, out conn.first.ux, out conn.first.uy);
                    conn.first.UpdatePosition(true);
                    conn.DoCreationFixup();
                    conn.InvalidateTemporary();
                    conn.Invalidate();
                }
                else if ((modif & Keys.Shift) == Keys.Shift)
                {
                    GuiObject obj = parent.FindItem(x, y, false);
                    if (obj != null)
                    {
                        parent.SelectedObjects.Add(obj);
                        obj.Invalidate();
                    }
                }
                else
                {
                    //   Left button click:
                    //      select
                    //      move, move multiple

                    GuiObject s = parent.FindItem(x, y, out moveux, out moveuy, false);
                    if (s == null)
                    {
                        parent.SelectedObjects.Clear();
                        action = MouseAction.Select;
                        selx   = x;
                        sely   = y;
                        return;
                    }

                    if (!s.selected)
                    {
                        parent.SelectedObjects.Clear();
                        parent.SelectedObjects.Add(s);
                    }

                    // deciding: to move, or not ...

                    moveitem = null;
                    movelist = null;
                    movestates.Clear();
                    original_selected = null;
                    GuiObject t = parent.FindItem(x, y, out moveux, out moveuy, true);
                    if (t != null)
                    {
                        if (t is IMoveRedirect)
                        {
                            if (t.selected)
                            {
                                original_selected = t;
                            }
                            moveitem = (t as IMoveRedirect).MoveRedirect(ref moveux, ref moveuy);
                        }
                        else if (t is IMoveMultiple && (t as IMoveMultiple).CanMoveInGroup)
                        {
                            movelist = new ArrayList();
                            if (!t.selected)
                            {
                                movelist.Add(t);
                            }
                            foreach (GuiObject o in parent.SelectedObjects)
                            {
                                if (o is IMoveMultiple && (o as IMoveMultiple).CanMoveInGroup)
                                {
                                    movelist.Add(o);
                                }
                            }
                            selx = x;
                            sely = y;
                        }
                        else if (t is IMoveable && (t as IMoveable).IsMoveable(x, y))
                        {
                            moveitem = t as IMoveable;
                        }

                        if (moveitem != null || movelist != null)
                        {
                            first_move = true;
                            action     = MouseAction.Move;
                        }
                        else if (t is IClickable)
                        {
                            (t as IClickable).LeftClick(false, x, y);
                        }
                    }
                }
            }
            else if (b == MouseButtons.Right)
            {
                ISelectable obj = parent.FindItem(x, y, true) as ISelectable;
                if (obj != null)
                {
                    if (obj is IDropMenu)
                    {
                        parent.SelectedObjects.Clear();
                        parent.SelectedObjects.Add(obj as GuiObject);

                        System.Windows.Forms.ContextMenu m = new ContextMenu();
                        (obj as IDropMenu).AddMenuItems(m, x, y);
                        if (m.MenuItems.Count > 0)
                        {
                            m.Show(parent.cview, new Point(realx, realy));
                        }
                    }
                }
                else
                {
                    action         = MouseAction.Scroll;
                    Cursor.Current = Cursors.Hand;
                    selx           = x;
                    sely           = y;
                    menurealx      = realx;
                    menurealy      = realy;
                    first_move     = true;
                }
            }
        }