glxheads: exercise multiple GLX connections (any key = exit)
Usage:
  glxheads xdisplayname ...
Example:
  glxheads :0 mars:0 venus:1
Name: :0
  Display:     0x19eb010
  Window:      0x4c00002
  Context:     0x1a039a0
  GL_VERSION:  1.4 Mesa 7.11
  GL_VENDOR:   Tungsten Graphics, Inc
  GL_RENDERER: Mesa DRI Intel(R) 945G