libxcb-xtest0-dbg 1.9.1-3ubuntu1 (amd64 binary) in ubuntu trusty

 This package contains the debugging symbols associated with
 libxcb-xtest, the xtest extension for the X C Binding. gdb will
 automatically use these symbols when debugging libxcb-xtest.
 .
 The XCB library provides an interface to the X Window System protocol,
 designed to replace the Xlib interface. XCB provides several advantages over
 Xlib:
 .
  * Size: small library and lower memory footprint
  * Latency hiding: batch several requests and wait for the replies later
  * Direct protocol access: one-to-one mapping between interface and protocol
  * Thread support: access XCB from multiple threads, with no explicit locking
  * Easy creation of new extensions: automatically generates interface from
    machine-parsable protocol descriptions