C / C++ / MFC

if( !IsWindow( m_YourTreeCtrl ) )
   return;

// Here, m_YourTreeCtrl can be accessed safely.

CRect treeRect;
treeRect.NormalizeRect();
CImageList *pImageList=new CImageList;
	
	
if(this->m_ctrlSetupTree.Create(WS_VISIBLE,treeRect,this,IDC_SETUP_TREE))
	{
		Beep(999,99);
		int i, icons=0;
		for (icons=0; RCanalTree::m_icons[icons]; icons++) {}
		pImageList->Create(16, 16, TRUE, icons,6);
		for (i=0; RCanalTree::m_icons[i]; i++)
		{
			pImageList->Add(AfxGetApp()->LoadIcon(RCanalTree::m_icons[i]));
		}
		// Assign the image list to all list and tree controls
		// so that icons can be used.	
		m_ctrlSetupTree.SetImageList(pImageList,TVSIL_NORMAL);
		
		// Instruct the Canal Manager to create a new system based on the information
		// in the Canal Structures database.
		
		
		if(this->m_oCanalManager.CreateNewDataStructures())
		{
			// Based on the data structures created in memory by the Canal Manager,
			// populate the setup tree.
			//this->m_ctrlSetupTree.Populate();
		}
		
	}
}

if(this->m_ctrlSetupTree.Create(WS_CHILD|WS_VISIBLE,treeRect,this,IDC_SETUP_TREE))
{
   ..... snip .....
}

if(this->m_ctrlSetupTree.Create(WS_CHILD|WS_VISIBLE|TVS_HASLINES,treeRect,this,IDC_SETUP_TREE))

void CSacmanSetupApplicationView::OnInitialUpdate()
{
	CFormView::OnInitialUpdate();
	GetParentFrame()->RecalcLayout();
	ResizeParentToFit();

		// Build the image list which will hold the icons
	// we want to use in the lists and trees.

	CRect treeRect;
	CImageList *pImageList=new CImageList;	
	My object is fine at this point	
		if(this->m_ctrlSetupTree)
		{
			
			Beep(999,99);
			int i, icons=0;
			for (icons=0; RCanalTree::m_icons[icons]; icons++) {}
			pImageList->Create(16, 16, TRUE, icons,6);
			for (i=0; RCanalTree::m_icons[i]; i++)
			{
				pImageList->Add(AfxGetApp()->LoadIcon(RCanalTree::m_icons[i]));
			}
			// Assign the image list to all list and tree controls
			// so that icons can be used.	
			m_ctrlSetupTree.SetImageList(pImageList,TVSIL_NORMAL);
			
			// Instruct the Canal Manager to create a new system based on the information
			// in the Canal Structures database.
			
Had to make sure it was displaying an object with data in it..	

m_ctrlSetupTree.SetCanalManagerPointer(this->m_oCanalManager.GetCanalManager());