SetLayeredWindowsAttributes пример:
import win32gui
import win32con
import winxpgui
import win32api
import subprocess
import time
subprocess.Popen("notepad.exe", shell=True)
time.sleep(1)
hwnd = win32gui.FindWindow(None, "New file - metapad") ## The caption of my empty notepad (MetaPad)
win32gui.SetWindowLong (hwnd, win32con.GWL_EXSTYLE, win32gui.GetWindowLong (hwnd, win32con.GWL_EXSTYLE ) | win32con.WS_EX_LAYERED )
winxpgui.SetLayeredWindowAttributes(hwnd, win32api.RGB(0,0,0), 180, win32con.LWA_ALPHA)