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oblitum
Asked: 2013-12-24 17:58:14 +0800 CST

Why wmctrl doesn't work for certain windows?

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francisco@Ubuntu:~$ wmctrl -l
0x02600006  0 Ubuntu Área de trabalho
0x03c00002  0 Ubuntu XdndCollectionWindowImp
0x03c00005  0 Ubuntu unity-launcher
0x03c00008  0 Ubuntu unity-panel
0x03c0000b  0 Ubuntu unity-dash
0x03c0000c  0 Ubuntu Hud
0x046000b3  0 Ubuntu How to make a window aways on top? - Stack Overflow - Mozilla Firefox
0x0520000b  0    N/A Qt Creator
0x05002396  0 Ubuntu francisco@Ubuntu: ~
0x0540000b  0    N/A backlight

For windows that have the machine name column as N/A I'm unable to send wmctrl commands like wmctrl -r "window name" -b add,above. Why? (also, I don't know why these windows are different regarding the machine name column...)

My initial intent was to send such command to the backlight window, a frameless Qt application. Using the window system menu and checking the "Always On Top" works for the window though. I just like a programmatic means of doing the same.

compiz

1 Answers

  1. Best Answer

    it's definitely a bug in wmctrl.
    after digging around wmctrl code, it seems that the bug is in translating window name strings to the corresponding Window ID (or XID). so wmctrl -r "window name" -b add,above is not reliable.

    as a workaround, use XID instead, i.e. wmctrl -i -r window_id -b add,above. in your case , wmctrl -i -r 0x0520000b -b add,above should work.

    most window management facilities are implemented as X window Properties. you can view all the properties of a window by a command -- xprop.

    NOTE:

    1. Windows that have the machine name column as N/A. the machine name property is WM_CLIENT_MACHINE. it's rarely used. and some GUI toolkits may not implement them.
      you can view a window's machine name property by run following command line and click the window

      shell> xprop | grep MACHINE

    2. As for Always On Top, it's another property value _NET_WM_STATE_ABOVE.
      to check it yourself, run following command line and click the window 

      shell> xprop | grep _NET_WM_STATE
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