private void MainPicBox_MouseUp(object sender, MouseEventArgs e)
        {
            endPos = e.Location;

            if (action == Action.transformX || action == Action.transformY || action == Action.transformZ)
            {
                mainScene.ApplyTransformation();
                mainScene.ResetTemp();
                action = Action.noAction;
                return;
            }
            mainScene.ResetTemp();

            if (action == Action.selecting && e.Button == MouseButtons.Left)
            {
                mouseLbutton = false;
                mainScene.SelectPoints(startPos.X, startPos.Y, endPos.X, endPos.Y);
                treeSelected_CheckedUpdate();
            }
            if (e.Button == MouseButtons.Right)
            {
                mainPicBox_ContextMenu.Show(Cursor.Position.X, Cursor.Position.Y);
            }
            if (action == Action.connecting && e.Button == MouseButtons.Left)
            {
                mouseLbutton = false;
                mainScene.ConnectPoints(startPos.X, startPos.Y, endPos.X, endPos.Y, 4, Color.FromArgb(255, rnd.Next(0, 255), rnd.Next(0, 255), rnd.Next(0, 255)));
            }

            UpdatePicBox();

            if (e.Button == MouseButtons.Middle)
            {
                mouseMidbutton = false;
            }

            if (e.Button == MouseButtons.Left)
            {
                mouseLbutton = false;
            }
            action = Action.noAction;
        }