Comment 7 for bug 1028274

Created attachment 65279
Workaround - Patch against Ubuntu 12.04 source (7.6)

This is https://bugs.launchpad.net/ubuntu/+source/x11-utils/+bug/1028274 and https://bugzilla.redhat.com/show_bug.cgi?id=808561

[Impact]
xwininfo segfaults if called with an out-of-range screen number.

[Test Case]
1. xwininfo -root -display :0.0
2. xwininfo -root -display :0.1

Actual Behavior:
 * First command passes
 * Second command segfaults
Expected Behavior:
 * First command passes
 * Second command returns an error message without segfaulting

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On Ubuntu 8.04 this error message used to be "cannot open display :0.1".

The problem could lie in libxcb (I'm no expert) xcb_connection_has_error() no longer returning true in the -display :0.1 case, but I've attached a patch for xwininfo anyway (sorry about the downstream format etc, not ready to jump into git). My lingering concern is over how many other bits of code use libxcb in this way, and may have had their assumptions broken. I.e. is the "right" place to fix this problem longer term in libxcb?