internal void AddSideChild(IDockElement ele, DockSide side)
{
switch (side)
{
case DockSide.Left:
LeftSide.Attach(ele);
break;
case DockSide.Right:
RightSide.Attach(ele);
break;
case DockSide.Top:
TopSide.Attach(ele);
break;
case DockSide.Bottom:
BottomSide.Attach(ele);
break;
}
}