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original post

I'm running ubuntu 10.04, using the openbox window manager.

There recently appeared a black rectangle with dimensions of about 100x200 pixels that's obscuring the contents of the display. wmctrl -l doesn't list anything that could be causing it. It appears on all desktops. It catches mouse focus, but xkill doesn't make it go away. It doesn't show up in the alt-tab cycle. Setting windows to "always on top" in the z-order does not prevent them from being obscured by this rectangle. Full-screen apps and video are also obscured by the rectangle.

So far, the only things that I've found are able to display without having this rectangle in the way are

  • other TTY sessions, meaning that hitting CTRL-ALT-F2 will give a console which is not obscured by the rectangle.
  • xlock. It is unaffected by this issue both when showing a screen saver and when asking for a password.

How can I get rid of the rectangle without killing my X session or any processes not responsible for it? Is resistance futile?


Thanks to cYrus I've learned to use xprop to get the PID of the window. It's got a pretty limited set of properties:

        Client accepts input or input focus: True
        Initial state is Normal State.
        window id # of group leader: 0x2000001
_NET_WM_USER_TIME_WINDOW(WINDOW): window id # 0x211bf8d
WM_CLIENT_LEADER(WINDOW): window id # 0x2000001
        program specified location: 0, 0
        program specified minimum size: 274 by 156
        program specified maximum size: 274 by 156
        window gravity: NorthWest
WM_CLASS(STRING) = "google-chrome", "Google-chrome"
WM_ICON_NAME(STRING) = "google-chrome"
_NET_WM_ICON_NAME(UTF8_STRING) = 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2d, 0x63, 0x68, 0x72, 0x6f, 0x6d, 0x65
WM_NAME(STRING) = "google-chrome"
_NET_WM_NAME(UTF8_STRING) = 0x67, 0x6f, 0x6f, 0x67, 0x6c, 0x65, 0x2d, 0x63, 0x68, 0x72, 0x6f, 0x6d, 0x65

The PID given is that of my top-level Chrome process (version 6.0.472.53, for those interested). I'm loathe to kill the process since it may cause me to lose track of the 40+ tabs I've currently got open and their assorted histories, so it would be great if there were some way to close or hide this window. Unfortunately, I'm not well-acquainted with X properties and am not sure how to go about doing this.

The window type indicates that it's a popup; I guess it didn't finish doing that. This would explain why it doesn't accept the window focus: i.e. although it catches mouse clicks, subsequent presses of alt-space bring up the window menu for another window.

I tried converting its type to NORMAL but I get

xprop: error: unsupported conversion for _NET_WM_WINDOW_TYPE(ATOM)

How can I manipulate this embryonic window in a way that will cause it to cease to obstruct the display?

share|improve this question
Does xprop + click on the rectangle give some useful informations? – cYrus Sep 9 '10 at 21:44
@cYrus: Yes, thanks. Looks like it's Chrome. You should make your comment an answer so I can accept it. – intuited Sep 9 '10 at 23:49
@cYrus: Any idea what property I would want to give it so that I can close it? Although it catches mouse clicks, it doesn't actually take the focus, so I can't use alt-space to get its menu. – intuited Sep 10 '10 at 0:02
Yeah, bottom line is that it's an overlay window (typically used for menus, but also sometimes for popups) that Chrome has created and forgotten about. cYrus's suggestion that you kill Chrome is the only thing I've found that works. I've tried "xkill" on the offending window, but it never worked. I actually prefer to kill Chrome rather than exit cleanly, because this way I know it will restore all my windows and tabs on restart. If anybody has a better way, I'd like to hear it. – Edward Falk Dec 3 '13 at 20:10
I switched over to Unity some time after posting this, and haven't had the problem recently. – intuited Dec 3 '13 at 21:13
up vote 2 down vote accepted

xprop + click on the rectangle to get some useful informations.

You can kill the process once you have the PID:

$ xprop | grep -i pid
$ kill -KILL 14712

Anyway, this should be the proper way to use xprop to change the _NET_WM_WINDOW_TYPE option (never tried that):

share|improve this answer
I ended up shutting down chrome the normal way, so I won't test your xprop command unless it happens again. Thanks. – intuited Sep 10 '10 at 19:46


% xwininfo -tree -root

to get an idea of which windows are there. the use this information to find out, if at the given position is a window or not and if: which one.

share|improve this answer

I've recently encountered similar problem with Chromium and KWin WM.

To avoid killing browser you can just make this window invisible:

  1. Get window ID with xprop+click as @cYrus proposed or with xwininfo+click
  2. Hide this window with xdotool windowunmap <ID>

P.S.: Setting _NET_WM_WINDOW_TYPE did not seem to affect it in any way.

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