PyGetMemory, PyGetBufferAddressAndLen, and PyGetString cannot recursively retrieve program descendant windows

[yjkt]

Expected behavior and actual behavior

Expected behavior

Using SECTION 2, the program is normal.

The program can run to print('Finished enumerating child windows') location。

xxxxxxxxxxxxxxxxxxxxxxxxx
Finished enumerating child windows
x: [8392952]

Actual behavior

Using SECTION 1, The program did not run to x and exited directly.

Steps to reproduce the problem

1. Run the 3D-tool program and open any 3D model file.
2. Click the Model Info button to open a panel
   
3. Running the following script, the code in Section1 cannot correctly obtain the Combox hwnd for Not assigned, and the program exits. But using code of Section2 can work normally

import win32gui
import win32api
import ctypes

# Define the required message constants
CB_GETCURSEL = 0x0147
CB_GETLBTEXT = 0x0148
CB_GETLBTEXTLEN = 0x0149

def get_combo_box_selected_value(hwnd):
    # Get the currently selected index
    index = win32api.SendMessage(hwnd, CB_GETCURSEL, 0, 0)
    
    if index == -1:
        print("No item selected.")
        return None
    
    # Get the length of the selected item's text
    text_length = win32api.SendMessage(hwnd, CB_GETLBTEXTLEN, index, 0)
    
    if text_length == -1:
        print("Failed to get text length.")
        return None
    
    # SECTION 1: Using PyGetMemory, PyGetBufferAddressAndLen, and PyGetString
    # Create a buffer to store the text
    length = text_length + 1
    buf = b'\0' * length
    win32gui.PyGetMemory(id(buf), length)
    win32api.SendMessage(hwnd, CB_GETLBTEXT, index, buf)
    addr, length = win32gui.PyGetBufferAddressAndLen(buf)
    text = win32gui.PyGetString(addr, length - 1)

    # SECTION 2: Using ctypes
    # Create a buffer to store the text
    # buffer = ctypes.create_unicode_buffer(text_length + 1)
    # win32api.SendMessage(hwnd, CB_GETLBTEXT, index, buffer)
    # text = buffer.value
    
    return text

def enum_child_windows_callback(hwnd, x):
    # Get the class name and title of the child window
    class_name = win32gui.GetClassName(hwnd)
    if class_name == 'TComboBox':
        window_text = get_combo_box_selected_value(hwnd)
        print(f"ComboBox text: {window_text}")
    else:
        window_text = win32gui.GetWindowText(hwnd)
        print(f"Window text: {window_text}")

    if class_name == 'TComboBox' and window_text == 'Not assigned':
        print('xxxxxxxxxxxxxxxxxxxxxxxxx')
        x.append(hwnd)
        return False

    return True  # Continue enumerating child windows

def enum_all_child_windows(parent_hwnd, x):
    win32gui.EnumChildWindows(parent_hwnd, enum_child_windows_callback, x)

if __name__ == "__main__":
    calculator_hwnd = win32gui.FindWindow(None, "3D-Tool")

    if calculator_hwnd:
        print(f"Found main window: Handle={hex(calculator_hwnd)}")
        x = []
        enum_all_child_windows(calculator_hwnd, x)
        print('Finished enumerating child windows')
        print('x:', x)
    else:
        print("Could not find the specified window.")

System information

Python version and distribution:
miniconda Python 3.12.8 x64 for window 11 pro, 24H2

pywin32 version:
pywin32 308