process id do id da janela

Question

Quando eu executo xprop -id <wid> em uma determinada ID do Windows para um aplicativo opengl (Ubuntu 12.04) eu recebo um monte de propriedades, mas não vejo _NET_WM_PID ;

$ xprop -id 0x4a00002 
_NET_WM_ICON_GEOMETRY(CARDINAL) = 0, 488, 64, 65
XKLAVIER_STATE(INTEGER) = 0, 0
_NET_WM_FULLSCREEN_MONITORS(CARDINAL) = 4294967295, 1852143205, 19456, 1645412352
_NET_WM_STATE(ATOM) = 
WM_STATE(WM_STATE):
        window state: Normal
        icon window: 0x0
_NET_FRAME_EXTENTS(CARDINAL) = 1, 1, 28, 1
_NET_WM_DESKTOP(CARDINAL) = 0
_NET_WM_ALLOWED_ACTIONS(ATOM) = _NET_WM_ACTION_MOVE, _NET_WM_ACTION_RESIZE, _NET_WM_ACTION_FULLSCREEN, _NET_WM_ACTION_MINIMIZE, _NET_WM_ACTION_SHADE, _NET_WM_ACTION_MAXIMIZE_HORZ, _NET_WM_ACTION_MAXIMIZE_VERT, _NET_WM_ACTION_CHANGE_DESKTOP, _NET_WM_ACTION_CLOSE, _NET_WM_ACTION_ABOVE, _NET_WM_ACTION_BELOW
WM_PROTOCOLS(ATOM): protocols  WM_DELETE_WINDOW
WM_LOCALE_NAME(STRING) = "C"
WM_HINTS(WM_HINTS):
        Initial state is Normal State.
WM_NORMAL_HINTS(WM_SIZE_HINTS):
        user specified location: 50, 50
        user specified size: 640 by 480
WM_CLIENT_MACHINE(STRING) = "gliese-581h"
WM_ICON_NAME(STRING) = "Full-Screen & Windowed Mode"
WM_NAME(STRING) = "Full-Screen & Windowed Mode"

como faço para acessar o processo pid associado ao id da janela?

    

Answer 1

Está presente nas janelas que o suportam:

$ xprop -id 0x0540019c| grep _NET_WM_PID
_NET_WM_PID(CARDINAL) = 25685

Mas nem todos fazem:

$ xprop -id 0x2000006| grep _NET_WM_PID
$

Tanto quanto sei, não há como acessar o PID para tal janela.