private void OnSpaceDisposed(object sender, EventArgs e)
{
// Unhook from events to prevent memory leaking
SpaceControl.Disposed -= new EventHandler(OnSpaceDisposed);
SpaceControl.WorkspaceCellAdding -= new EventHandler<WorkspaceCellEventArgs>(OnSpaceCellAdding);
SpaceControl.PageDrop -= new EventHandler<PageDropEventArgs>(RaiseSpacePageDrop);
// Raise event to indicate the space control has been removed
RaiseRemoved();
}