Why can't I see tree view's nodes when I subclass it this way ?

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C++

Win32

Hello everyone!

I would like to start by saying thanks to everyone who takes some time to view this thread and try to help.

I have subclassed tree view in my main window to make his background transparent, which works fine, but its items are not painted at all!

I am inexperienced in subclassing, so I ask more experienced members to help me modify following code, so I can get transparent tree view with all nodes displayed properly:

// variable for storing old window procedure

static WNDPROC wp;

LRESULT CALLBACK wpTree(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
         switch(message)
	 {

	  case WM_PAINT:
		{
		        PAINTSTRUCT ps;

		        HDC hdc = BeginPaint(hWnd, &ps), 
                             hdcMem = CreateCompatibleDC(hdc);
		
 			RECT r;

                        // get tree view's client rectangle

			GetClientRect( hWnd, &r );

                        /* create compatible bitmap, size of tree's client 
                                                                    rectangle */

			HBITMAP bmp = CreateCompatibleBitmap( hdc, 
                                                              r.right - r.left, 
                                                              r.bottom - r.top ) , 
                                bmpOld;

			bmpOld = (HBITMAP)SelectObject( hdcMem, bmp );

                        // Blt it and make background transparent

			TransparentBlt( hdc, 0, 0, 
                                        r.right - r.left, 
                                        r.bottom - r.top, 
                                        hdcMem, 0, 0, 
                                        r.right - r.left,
                                        r.bottom - r.top, 
                                        RGB( 0, 0, 0 ) );

                        // take care for memory leak
  
			SelectObject( hdcMem, bmpOld );

                        // cleanup

			DeleteObject(bmp);

			DeleteDC(hdcMem);

			EndPaint(hWnd, &ps);

		}
		return 0L;

	case WM_ERASEBKGND:
		return 0L;
	}

	return CallWindowProc( wp, hWnd, message, wParam, lParam );
}

This is how I have subclassed tree in main window procedure:

case WM_CREATE:
    {
         // create tree view

         hwndTV = CreateWindowEx( ... );

         // store old procedure

         wp = (WNDPROC)GetWindowLongPtr( hwndTV, GWL_WNDPROC);

         // subclass tree

         SetWindowLongPtr( hwndTV, GWL_WNDPROC, (LONG)wpTree );

         // add some nodes to the tree
               .
               .
               .
    }

Code example, or snippet would be very helpful, but I would also appreciate written instructions as well, but make them detailed please, since I am not very experienced.

I work in MS Visual Studio Express 2008, on Windows XP, in C++, using pure WIN32 API.

That would be all, again I thank everyone who tries to help.Thank you very very much!