Limit docking pane direction

Try catch actions:

if (wParam == XTP_DPN_ACTION)
 {
  XTP_DOCKINGPANE_ACTION* pAction = (XTP_DOCKINGPANE_ACTION*)lParam;

  if (pAction->action == xtpPaneActionDocking)
  {
   if (pAction->pDockContainer->GetType() != xtpPaneTypeTabbedContainer && (pAction->dockDirection != xtpPaneDockLeft && pAction->dockDirection != xtpPaneDockRight))
   {
    pAction->bCancel = TRUE;
   }

  }

  return TRUE;
 }