from subprocess import *

name = "firefox"
positionX = 350
positionY = 150
width = 500
height = 400
windowID = Popen(["xdotool", "search", "--onlyvisible", "--name", name], stdout=PIPE).communicate()[0].strip()
Popen(["xdotool", "windowsize", windowID, str(width), str(height)], stdout=PIPE).communicate()
Popen(["xdotool", "windowmove", windowID, str(positionX), str(positionY)], stdout=PIPE).communicate()
Popen(["xdotool", "windowactivate", windowID], stdout=PIPE).communicate()[0].strip()

#windowminimize ums ein fenster klein zu machen