semi-transparency with xlib and pytqt

from Xlib import display, Xatom, X
from Xlib.protocol import request
from Xlib.xobject.drawable import Pixmap
import PIL.Image

_display = display.Display()
screen = _display.screen()
root = screen.root
XROOTPMAP_ID = _display.intern_atom("_XROOTPMAP_ID")
result = root.get_full_property(XROOTPMAP_ID, Xatom.PIXMAP)
print result
root_pm_id = result.value[0]
print root_pm_id

src_drawable = Pixmap(_display.display, root_pm_id)
geometry = src_drawable.get_geometry()
#img_data = src_drawable.get_image(0, 0, geometry.width, geometry.height, X.ZPixmap, 0xffffffff)
#raw = src_drawable.get_image(0, 0, geometry.width, geometry.height, X.ZPixmap, 0xffffffff)
#image = PIL.Image.frombytes("RGB", (geometry.width, geometry.height), raw.data, "raw", "BGRX")
#image.show()

#pm = TQPixmap(geometry.width, geometry.height)
# does not work:
#dst_drawable = Pixmap(_display.display, pm.handle())
#gc = src_drawable.create_gc()

#dst_drawable.copy_area(gc, src_drawable, 0, 0, geometry.width, geometry.height, 0, 0)